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Lovatti G, Nitta M, Javad Safari M, Gianoli C, Pinto M, Dedes G, Zoglauer A, Thirolf PG, Parodi K. Design study of a novel geometrical arrangement for an in-beam small animal positron emission tomography scanner. Phys Med Biol 2023; 68:235005. [PMID: 37906973 DOI: 10.1088/1361-6560/ad0879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 10/31/2023] [Indexed: 11/02/2023]
Abstract
Objective.We designed a geometrical solution for a small animal in-beam positron emission tomography (PET) scanner to be used in the project SIRMIO (Small animal proton irradiator for research in molecular image-guided radiation-oncology). The system is based on 56 scintillator blocks of pixelated LYSO crystals. The crystals are arranged providing a pyramidal-step shape to optimize the geometrical coverage in a spherical configuration.Approach.Different arrangements have been simulated and compared in terms of spatial resolution and sensitivity. The chosen setup enables us to reach a good trade-off between a solid angle coverage and sufficient available space for the integration of additional components of the first design prototype of the SIRMIO platform. The possibility of moving the mouse holder inside the PET scanner furthermore allows for achieving the optimum placement of the irradiation area for all the possible tumor positions in the body of the mouse. The work also includes a study of the scintillator material where LYSO and GAGG are compared with a focus on the random coincidence noise due to the natural radioactivity of Lutetium in LYSO, justifying the choice of LYSO for the development of the final system.Main results.The best imaging performance can be achieved with a sub-millimeter spatial resolution and sensitivity of 10% in the center of the scanner, as verified in thorough simulations of point sources. The simulation of realistic irradiation scenarios of proton beams in PMMA targets with/without air gaps indicates the ability of the proposed PET system to detect range shifts down to 0.2 mm.Significance.The presented results support the choice of the identified optimal design for a novel spherical in-beam PET scanner which is currently under commissioning for application to small animal proton and light ion irradiation, and which might find also application, e.g. for biological image-guidance in x-ray irradiation.
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Affiliation(s)
- Giulio Lovatti
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Munetaka Nitta
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Mohammad Javad Safari
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Chiara Gianoli
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Marco Pinto
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Georgios Dedes
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Andreas Zoglauer
- Space Sciences Laboratory, University of California, Berkeley, United States of America
| | - Peter G Thirolf
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Katia Parodi
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
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Kraemer S, Moens J, Athanasakis-Kaklamanakis M, Bara S, Beeks K, Chhetri P, Chrysalidis K, Claessens A, Cocolios TE, Correia JGM, Witte HD, Ferrer R, Geldhof S, Heinke R, Hosseini N, Huyse M, Köster U, Kudryavtsev Y, Laatiaoui M, Lica R, Magchiels G, Manea V, Merckling C, Pereira LMC, Raeder S, Schumm T, Sels S, Thirolf PG, Tunhuma SM, Van Den Bergh P, Van Duppen P, Vantomme A, Verlinde M, Villarreal R, Wahl U. Observation of the radiative decay of the 229Th nuclear clock isomer. Nature 2023; 617:706-710. [PMID: 37225880 DOI: 10.1038/s41586-023-05894-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 02/28/2023] [Indexed: 05/26/2023]
Abstract
The radionuclide thorium-229 features an isomer with an exceptionally low excitation energy that enables direct laser manipulation of nuclear states. It constitutes one of the leading candidates for use in next-generation optical clocks1-3. This nuclear clock will be a unique tool for precise tests of fundamental physics4-9. Whereas indirect experimental evidence for the existence of such an extraordinary nuclear state is substantially older10, the proof of existence has been delivered only recently by observing the isomer's electron conversion decay11. The isomer's excitation energy, nuclear spin and electromagnetic moments, the electron conversion lifetime and a refined energy of the isomer have been measured12-16. In spite of recent progress, the isomer's radiative decay, a key ingredient for the development of a nuclear clock, remained unobserved. Here, we report the detection of the radiative decay of this low-energy isomer in thorium-229 (229mTh). By performing vacuum-ultraviolet spectroscopy of 229mTh incorporated into large-bandgap CaF2 and MgF2 crystals at the ISOLDE facility at CERN, photons of 8.338(24) eV are measured, in agreement with recent measurements14-16 and the uncertainty is decreased by a factor of seven. The half-life of 229mTh embedded in MgF2 is determined to be 670(102) s. The observation of the radiative decay in a large-bandgap crystal has important consequences for the design of a future nuclear clock and the improved uncertainty of the energy eases the search for direct laser excitation of the atomic nucleus.
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Affiliation(s)
- Sandro Kraemer
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium.
- Ludwig-Maximilians-Universität München, Garching, Germany.
| | - Janni Moens
- KU Leuven, Quantum Solid State Physics, Leuven, Belgium
| | | | - Silvia Bara
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium
| | - Kjeld Beeks
- Institute for Atomic and Subatomic Physics, TU Wien, Vienna, Austria
| | | | | | - Arno Claessens
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium
| | | | - João G M Correia
- Centro de Ciências e Tecnologias Nucleares, Departamento de Engenharia e Ciências Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Bobadela, Portugal
| | - Hilde De Witte
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium
| | - Rafael Ferrer
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium
| | - Sarina Geldhof
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium
| | | | - Niyusha Hosseini
- Institute for Atomic and Subatomic Physics, TU Wien, Vienna, Austria
| | - Mark Huyse
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium
| | | | - Yuri Kudryavtsev
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium
| | - Mustapha Laatiaoui
- Department Chemie, Johannes-Gutenberg-Universität, Mainz, Germany
- Helmholtz-Institut Mainz, Mainz, Germany
- GSI Helmholtzzentrum für Scherionenforschung, Darmstadt, Germany
| | - Razvan Lica
- CERN, Geneva, Switzerland
- Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania
| | | | - Vladimir Manea
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium
| | | | | | - Sebastian Raeder
- Helmholtz-Institut Mainz, Mainz, Germany
- GSI Helmholtzzentrum für Scherionenforschung, Darmstadt, Germany
| | - Thorsten Schumm
- Institute for Atomic and Subatomic Physics, TU Wien, Vienna, Austria
| | - Simon Sels
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium
| | | | | | | | - Piet Van Duppen
- KU Leuven, Instituut voor Kern- en Stralingsfysica, Leuven, Belgium
| | | | | | | | - Ulrich Wahl
- Centro de Ciências e Tecnologias Nucleares, Departamento de Engenharia e Ciências Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Bobadela, Portugal
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Kawula M, Binder TM, Liprandi S, Viegas R, Parodi K, Thirolf PG. Sub-millimeter precise photon interaction position determination in large monolithic scintillators via convolutional neural network algorithms. Phys Med Biol 2021; 66. [PMID: 34062523 DOI: 10.1088/1361-6560/ac06e2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 06/01/2021] [Indexed: 11/11/2022]
Abstract
In this work, we present the development and application of a convolutional neural network (CNN)-based algorithm to precisely determine the interaction position ofγ-quanta in large monolithic scintillators. Those are used as an absorber component of a Compton camera (CC) system under development for ion beam range verification via prompt-gamma imaging. We examined two scintillation crystals: LaBr3:Ce and CeBr3. Each crystal had dimensions of 50.8 mm × 50.8 mm × 30 mm and was coupled to a 64-fold segmented multi-anode photomultiplier tube (PMT) with an 8 × 8 pixel arrangement. We determined the spatial resolution for three photon energies of 662, 1.17 and 1.33 MeV obtained from 2D detector scans with tightly collimated137Cs and60Co photon sources. With the new algorithm we achieved a spatial resolution for the CeBr3 crystal below 1.11(8) mm and below 0.98(7) mm for the LaBr3:Ce detector for all investigated energies between 662 keV and 1.33 MeV. We thereby improved the performance by more than a factor of 2.5 compared to the previously used categorical average pattern algorithm, which is a variation of the well-established k-nearest neighbor algorithm. The trained CNN has a low memory footprint and enables the reconstruction of up to 104events per second with only one GPU. Those improvements are crucial on the way to future clinicalin vivoapplicability of the CC for ion beam range verification.
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Affiliation(s)
- M Kawula
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Garching b. München, Germany
| | - T M Binder
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Garching b. München, Germany.,KETEK GmbH, Munich, Germany
| | - S Liprandi
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Garching b. München, Germany
| | - R Viegas
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Garching b. München, Germany.,University of Coimbra, Portugal
| | - K Parodi
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Garching b. München, Germany
| | - P G Thirolf
- Department of Medical Physics, Ludwig-Maximilians-Universität München, Garching b. München, Germany
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Binder T, Kang HG, Nitta M, Schneider F, Yamaya T, Parodi K, Wiest F, Thirolf PG. Performance evaluation of a staggered three-layer DOI PET detector using a 1 mm LYSO pitch with PETsys TOFPET2 ASIC: comparison of HAMAMATSU and KETEK SiPMs. Phys Med Biol 2021; 66. [PMID: 33906179 DOI: 10.1088/1361-6560/abfbf3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 04/27/2021] [Indexed: 11/11/2022]
Abstract
In this study, we propose a staggered three-layer depth-of-interaction (DOI) detector with a 1 mm crystal pitch and 19.8 mm total crystal thickness for a high-resolution and high-sensitivity small animal in-beam PET scanner. A three-layered stacked LYSO scintillation array (0.9 × 0.9 × 6.6 mm3crystals, 23 × 22 mm2surface area) read out by a SiPM array (8 × 8 channels, 3 × 3 mm2active area/channel and 50μm microcell size) with data acquisition, signal processing and digitization performed using the PETsys Electronics Evaluations kit (based on the TOFPET v2c ASIC) builds a DOI LYSO detector block. The performance of the DOI detector was evaluated in terms of crystal resolvability, energy resolution, and coincidence resolving time (CRT). A comparative performance evaluation of the staggered three-layer LYSO block was conducted with two different SiPM arrays from KETEK and HAMAMATSU. 100% (KETEK) and 99.8% (HAMAMATSU) of the crystals were identified, by using a flood irradiation the front- and back-side. The average energy resolutions for the 1st, 2nd, and 3rd layers were 16.5 (±2.3)%, 20.9(±4.0)%, and 32.7 (±21.0)% (KETEK) and 19.3 (±3.5)%, 21.2 (±4.1)%, and 26.6 (±10.3)% (HAMAMATSU) for the used SiPM arrays. The measured CRTs (FWHM) for the 1st, 2nd, and 3rd layers were 532 (±111) ps, 463 (±108) ps, and 447 (±111) ps (KETEK) and 402 (±46) ps, 392 (±54) ps, and 408 (±196) ps (HAMAMATSU). In conclusion, the performance of the staggered three-layer DOI detector with 1 mm LYSO pitch and 19.8 mm total crystal thickness was fully characterized. The feasibility of a highly performing readout of a high resolution DOI PET detector via SiPM arrays from KETEK and HAMAMATSU employing the PETsys TOFPET v2c ASIC could be demonstrated.
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Affiliation(s)
- Tim Binder
- Ludwig-Maximilians-Universität, Munich, Germany.,KETEK GmbH, Munich, Germany
| | - Han Gyu Kang
- Institute for Quantum Medical Science, National Institutes for Quantum and Radiological Science and Technology (QST), Chiba, Japan
| | | | | | - Taiga Yamaya
- Institute for Quantum Medical Science, National Institutes for Quantum and Radiological Science and Technology (QST), Chiba, Japan
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5
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Englbrecht FS, Döpp A, Hartmann J, Lindner FH, Groß ML, Wirth HF, Thirolf PG, Karsch S, Schreiber J, Parodi K, Dedes G. Radiation protection modelling for 2.5 Petawatt-laser production of ultrashort x-ray, proton and ion bunches: Monte Carlo model of the Munich CALA facility. J Radiol Prot 2020; 40:1048-1073. [PMID: 32702682 DOI: 10.1088/1361-6498/aba8e4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
The 'Centre for Advanced Laser Applications' (CALA) is a new research institute for laser-based acceleration of electron beams for brilliant x-ray generation, laser-driven sub-nanosecond bunches of protons and heavy ions for biomedical applications like imaging and tumour therapy as well as for nuclear and high-field physics.The radiation sources emerging from experiments using the up to 2.5 petawatt laser pulses with 25 femtosecond duration will be mixed particle-species of high intensity, high energy and pulsed, thus posing new challenges compared to conventional radiation protection. Such worldwide pioneering laser experiments result in source characteristics that require careful a-priori radiation safety simulations.The FLUKA Monte-Carlo code was used to model the five CALA experimental caves, including the corridors, halls and air spaces surrounding the caves. Beams of electrons (<5 GeV), protons (<200 MeV),12C (<400MeV/u) and197Au (<10MeV/u) ions were simulated using spectra, divergences and bunch-charges based on expectations from recent scientific progress.Simulated dose rates locally can exceed 1.5 kSv h-1inside beam dumps. Vacuum pipes in the cave walls for laser transport and extraction channels for the generated x-rays result in small dose leakage to neighboring areas. Secondary neutrons contribute to most of the prompt dose rate outside caves into which the beam is delivered. This secondary radiation component causes non-negligible dose rates to occur behind walls to which large fluences of secondary particles are directed.By employing adequate beam dumps matched to beam-divergence, magnets, passive shielding and laser pulse repetition limits, average dose rates in- and outside the experimental building stay below design specifications (<0.5μSv h-1) for unclassified areas,<2.5μSv h-1for supervised areas,<7.5μSv h-1maximum local dose rate) and regulatory limits (<1mSv a-1for unclassified areas).
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Affiliation(s)
- Franz S Englbrecht
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
- Author to whom any correspondence should be addressed
| | - Andreas Döpp
- Chair of Experimental Physics - Laser Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - Jens Hartmann
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - Florian H Lindner
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - Martin L Groß
- Laboratory for Extreme Photonics, Ludwig-Maximilians-Universität München, Am Coulombwall 1a, 85748 Garching bei München, Germany
| | - Hans-F Wirth
- Laboratory for Extreme Photonics, Ludwig-Maximilians-Universität München, Am Coulombwall 1a, 85748 Garching bei München, Germany
| | - Peter G Thirolf
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - Stefan Karsch
- Chair of Experimental Physics - Laser Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - Jörg Schreiber
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
- Max Planck Institute of Quantum Optics, Hans-Kopfermann-Straße 1, 85748 Garching bei München, Germany
| | - Katia Parodi
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - George Dedes
- Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
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6
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Bilous PV, Bekker H, Berengut JC, Seiferle B, von der Wense L, Thirolf PG, Pfeifer T, López-Urrutia JRC, Pálffy A. Electronic Bridge Excitation in Highly Charged ^{229}Th Ions. Phys Rev Lett 2020; 124:192502. [PMID: 32469560 DOI: 10.1103/physrevlett.124.192502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 03/04/2020] [Accepted: 04/16/2020] [Indexed: 06/11/2023]
Abstract
The excitation of the 8 eV ^{229m}Th isomer through the electronic bridge mechanism in highly charged ions is investigated theoretically. By exploiting the rich level scheme of open 4f orbitals and the robustness of highly charged ions against photoionization, a pulsed high-intensity optical laser can be used to efficiently drive the nuclear transition by coupling it to the electronic shell. We show how to implement a promising electronic bridge scheme in an electron beam ion trap starting from a metastable electronic state. This setup would avoid the need for a tunable vacuum ultraviolet laser. Based on our theoretical predictions, determining the isomer energy with an uncertainty of 10^{-5} eV could be achieved in one day of measurement time using realistic laser parameters.
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Affiliation(s)
- Pavlo V Bilous
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany
| | - Hendrik Bekker
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany
- Department of Physics, Columbia University, 538 West 120th Street, New York, New York 10027-5255, USA
| | - Julian C Berengut
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany
- University of New South Wales, Sydney NSW 2052, Australia
| | - Benedict Seiferle
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, D-85748 Garching, Germany
| | - Lars von der Wense
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, D-85748 Garching, Germany
| | - Peter G Thirolf
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, D-85748 Garching, Germany
| | - Thomas Pfeifer
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany
| | | | - Adriana Pálffy
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany
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7
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Parodi K, Assmann W, Belka C, Bortfeldt J, Clevert DA, Dedes G, Kalunga R, Kundel S, Kurichiyanil N, Lämmer P, Lascaud J, Lauber K, Lovatti G, Meyer S, Nitta M, Pinto M, Safari MJ, Schnürle K, Schreiber J, Thirolf PG, Wieser HP, Würl M. Towards a novel small animal proton irradiation platform: the SIRMIO project. Acta Oncol 2019; 58:1470-1475. [PMID: 31271091 DOI: 10.1080/0284186x.2019.1630752] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Background: Precision small animal radiotherapy research is a young emerging field aiming to provide new experimental insights into tumor and normal tissue models in different microenvironments, to unravel complex mechanisms of radiation damage in target and non-target tissues and assess efficacy of novel therapeutic strategies. For photon therapy, modern small animal radiotherapy research platforms have been developed over the last years and are meanwhile commercially available. Conversely, for proton therapy, which holds potential for an even superior outcome than photon therapy, no commercial system exists yet. Material and methods: The project SIRMIO (Small Animal Proton Irradiator for Research in Molecular Image-guided Radiation-Oncology) aims at realizing and demonstrating an innovative portable prototype system for precision image-guided small animal proton irradiation, suitable for installation at existing clinical treatment facilities. The proposed design combines precise dose application with in situ multi-modal anatomical image guidance and in vivo verification of the actual treatment delivery. Results and conclusions: This manuscript describes the status of the different components under development, featuring a dedicated beamline for degradation and focusing of clinical proton beams, along with novel detector systems for in situimaging and range verification. The foreseen workflow includes pre-treatment proton transmission imaging, complemented by ultrasonic tumor localization, for treatment planning and position verification, followed by image-guided delivery with on site range verification by means of ionoacoustics (for pulsed beams) and positron-emission-tomography (PET, for continuous beams). The proposed compact and cost-effective system promises to open a new era in small animal proton therapy research, contributing to the basic understanding of in vivo radiation action to identify areas of potential breakthroughs for future translation into innovative clinical strategies.
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Affiliation(s)
- Katia Parodi
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Walter Assmann
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Claus Belka
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
- German Cancer Consortium (DKTK), Partner Site Munich, Munich, Germany
| | - Jonathan Bortfeldt
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Dirk-André Clevert
- Department of Radiology, Interdisziplinäres Ultraschall-Zentrum, University Hospital, LMU Munich, Munich, Germany
| | - George Dedes
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Ronaldo Kalunga
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Sonja Kundel
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Neeraj Kurichiyanil
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Paulina Lämmer
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Julie Lascaud
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Kirsten Lauber
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
- German Cancer Consortium (DKTK), Partner Site Munich, Munich, Germany
| | - Giulio Lovatti
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Sebastian Meyer
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Munetaka Nitta
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Marco Pinto
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Mohammad J. Safari
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Katrin Schnürle
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Jörg Schreiber
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Peter G. Thirolf
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Hans-Peter Wieser
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
| | - Matthias Würl
- Department of Medical Physics, Ludwig-Maximilians-Universität München (LMU Munich), Munich, Germany
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8
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Seiferle B, von der Wense L, Bilous PV, Amersdorffer I, Lemell C, Libisch F, Stellmer S, Schumm T, Düllmann CE, Pálffy A, Thirolf PG. Energy of the 229Th nuclear clock transition. Nature 2019; 573:243-246. [DOI: 10.1038/s41586-019-1533-4] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 07/23/2019] [Indexed: 11/09/2022]
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9
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Abstract
A methodology is described to generate an isotopically pure 229Th ion beam in the 2+ and 3+ charge states. This ion beam enables one to investigate the low-lying isomeric first excited state of 229Th at an excitation energy of about 7.8(5) eV and a radiative lifetime of up to 104 seconds. The presented method allowed for a first direct identification of the decay of the thorium isomer, laying the foundations to study its decay properties as prerequisite for an optical control of this nuclear transition. High energy 229Th ions are produced in the α decay of a radioactive 233U source. The ions are thermalized in a buffer-gas stopping cell, extracted and subsequently an ion beam is formed. This ion beam is mass purified by a quadrupole-mass separator to generate a pure ion beam. In order to detect the isomeric decay, the ions are collected on the surface of a micro-channel plate detector, where electrons, as emitted in the internal conversion decay of the isomeric state, are observed.
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10
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Lindner FH, Bin JH, Englbrecht F, Haffa D, Bolton PR, Gao Y, Hartmann J, Hilz P, Kreuzer C, Ostermayr TM, Rösch TF, Speicher M, Parodi K, Thirolf PG, Schreiber J. A novel approach to electron data background treatment in an online wide-angle spectrometer for laser-accelerated ion and electron bunches. Rev Sci Instrum 2018; 89:013301. [PMID: 29390656 DOI: 10.1063/1.5001990] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Laser-based ion acceleration is driven by electrical fields emerging when target electrons absorb laser energy and consecutively leave the target material. A direct correlation between these electrons and the accelerated ions is thus to be expected and predicted by theoretical models. We report on a modified wide-angle spectrometer, allowing the simultaneous characterization of angularly resolved energy distributions of both ions and electrons. Equipped with online pixel detectors, the RadEye1 detectors, the investigation of this correlation gets attainable on a single shot basis. In addition to first insights, we present a novel approach for reliably extracting the primary electron energy distribution from the interfering secondary radiation background. This proves vitally important for quantitative extraction of average electron energies (temperatures) and emitted total charge.
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Affiliation(s)
- F H Lindner
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - J H Bin
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - F Englbrecht
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - D Haffa
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - P R Bolton
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - Y Gao
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - J Hartmann
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - P Hilz
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - C Kreuzer
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - T M Ostermayr
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - T F Rösch
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - M Speicher
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - K Parodi
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - P G Thirolf
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - J Schreiber
- Lehrstuhl für Experimentalphysik - Medizinische Physik, Fakultät für Physik, Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
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11
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von der Wense L, Seiferle B, Stellmer S, Weitenberg J, Kazakov G, Pálffy A, Thirolf PG. A Laser Excitation Scheme for ^{229m}Th. Phys Rev Lett 2017; 119:132503. [PMID: 29341722 DOI: 10.1103/physrevlett.119.132503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Indexed: 06/07/2023]
Abstract
Direct laser excitation of the lowest known nuclear excited state in ^{229}Th has been a long-standing objective. It is generally assumed that reaching this goal would require a considerably reduced uncertainty of the isomer's excitation energy compared to the presently adopted value of (7.8±0.5) eV. Here we present a direct laser excitation scheme for ^{229m}Th, which circumvents this requirement. The proposed excitation scheme makes use of already existing laser technology and therefore paves the way for nuclear laser spectroscopy. In this concept, the recently experimentally observed internal-conversion decay channel of the isomeric state is used for probing the isomeric population. A signal-to-background ratio of better than 10^{4} and a total measurement time of less than three days for laser scanning appear to be achievable.
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Affiliation(s)
| | | | | | | | | | - Adriana Pálffy
- Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
| | - Peter G Thirolf
- Ludwig-Maximilians-Universität München, 85748 Garching, Germany
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12
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Lehrack S, Assmann W, Bertrand D, Henrotin S, Herault J, Heymans V, Stappen FV, Thirolf PG, Vidal M, Van de Walle J, Parodi K. Submillimeter ionoacoustic range determination for protons in water at a clinical synchrocyclotron. Phys Med Biol 2017; 62:L20-L30. [PMID: 28742053 DOI: 10.1088/1361-6560/aa81f8] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Proton ranges in water between 145 MeV to 227 MeV initial energy have been measured at a clinical superconducting synchrocyclotron using the acoustic signal induced by the ion dose deposition (ionoacoustic effect). Detection of ultrasound waves was performed by a very sensitive hydrophone and signals were stored in a digital oscilloscope triggered by secondary prompt gammas. The ionoacoustic range measurements were compared to existing range data from a calibrated range detector setup on-site and agreement of better than 1 mm was found at a Bragg peak dose of about 10 Gy for 220 MeV initial proton energy, compatible with the experimental errors. Ionoacoustics has thus the potential to measure the Bragg peak position with submillimeter accuracy during proton therapy, possibly correlated with ultrasound tissue imaging.
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Affiliation(s)
- Sebastian Lehrack
- Department of Medical Physics, Ludwig-Maximilians-Universität München, 85748 Garching b. München, Germany
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13
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Abstract
The first excited isomeric state of ^{229}Th possesses the lowest energy among all known excited nuclear states. The expected energy is accessible with today's laser technology and in principle allows for a direct optical laser excitation of the nucleus. The isomer decays via three channels to its ground state (internal conversion, γ decay, and bound internal conversion), whose strengths depend on the charge state of ^{229m}Th. We report on the measurement of the internal-conversion decay half-life of neutral ^{229m}Th. A half-life of 7±1 μs has been measured, which is in the range of theoretical predictions and, based on the theoretically expected lifetime of ≈10^{4} s of the photonic decay channel, gives further support for an internal conversion coefficient of ≈10^{9}, thus constraining the strength of a radiative branch in the presence of internal conversion.
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Affiliation(s)
- Benedict Seiferle
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - Lars von der Wense
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
| | - Peter G Thirolf
- Ludwig-Maximilians-Universität München, Am Coulombwall 1, 85748 Garching bei München, Germany
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14
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Aldawood S, Castelhano I, Gernhäuser R, Van Der Kolff H, Lang C, Liprandi S, Lutter R, Maier L, Marinšek T, Schaart DR, Parodi K, Thirolf PG. Comparative Characterization Study of a LaBr3(Ce) Scintillation Crystal in Two Surface Wrapping Scenarios: Absorptive and Reflective. Front Oncol 2015; 5:270. [PMID: 26697405 PMCID: PMC4670858 DOI: 10.3389/fonc.2015.00270] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 11/19/2015] [Indexed: 11/13/2022] Open
Abstract
The properties of a 50 mm × 50 mm × 30 mm monolithic LaBr3:Ce scintillator crystal coupled to a position-sensitive multi-anode photomultiplier (PMT, Hamamatsu H9500), representing the absorbing detector of a Compton camera under study for online ion (proton) beam range verification in hadron therapy, was evaluated in combination with either absorptive or reflective crystal surface coating. This study covered an assessment of the energy and position-dependent energy resolution, exhibiting a factor of 2.5–3.5 improvement for the reflectively wrapped crystal at 662 keV. The spatial dependency was investigated using a collimated 137Cs source, showing a steep degradation of the energy resolution at the edges and corners of the absorptively wrapped crystal. Furthermore, the time resolution was determined to be 273 ps (FWHM) and 536 ps (FWHM) with reflective and absorptive coating, respectively, using a 60Co source. In contrast, the light spread function (LSF) of the light amplitude distribution on the PMT segments improved for the absorptively wrapped detector. Both wrapping modalities showed almost no differences in the energy-dependent photopeak detection efficiency.
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Affiliation(s)
- Saad Aldawood
- Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany ; Department of Physics and Astronomy, King Saud University , Riyadh , Saudi Arabia
| | - Ines Castelhano
- Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany ; Faculty of Science, University of Lisbon , Lisbon , Portugal
| | - Roman Gernhäuser
- Physik Department E12, Technical University Munich , Garching , Germany
| | - Hugh Van Der Kolff
- Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany ; Faculty of Applied Science, Radiation Science and Technology, Delft University of Technology , Delft , Netherlands
| | - Christian Lang
- Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany
| | - Silvia Liprandi
- Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany
| | - Rudolf Lutter
- Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany
| | - Ludwig Maier
- Physik Department E12, Technical University Munich , Garching , Germany
| | - Tim Marinšek
- Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany
| | - Dennis R Schaart
- Faculty of Applied Science, Radiation Science and Technology, Delft University of Technology , Delft , Netherlands
| | - Katia Parodi
- Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany
| | - Peter G Thirolf
- Faculty of Physics, Ludwig-Maximilians-University Munich , Munich , Germany
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15
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Assmann W, Kellnberger S, Reinhardt S, Lehrack S, Edlich A, Thirolf PG, Moser M, Dollinger G, Omar M, Ntziachristos V, Parodi K. Ionoacoustic characterization of the proton Bragg peak with submillimeter accuracy. Med Phys 2015; 42:567-74. [PMID: 25652477 DOI: 10.1118/1.4905047] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
PURPOSE Range verification in ion beam therapy relies to date on nuclear imaging techniques which require complex and costly detector systems. A different approach is the detection of thermoacoustic signals that are generated due to localized energy loss of ion beams in tissue (ionoacoustics). Aim of this work was to study experimentally the achievable position resolution of ionoacoustics under idealized conditions using high frequency ultrasonic transducers and a specifically selected probing beam. METHODS A water phantom was irradiated by a pulsed 20 MeV proton beam with varying pulse intensity and length. The acoustic signal of single proton pulses was measured by different PZT-based ultrasound detectors (3.5 and 10 MHz central frequencies). The proton dose distribution in water was calculated by Geant4 and used as input for simulation of the generated acoustic wave by the matlab toolbox k-WAVE. RESULTS In measurements from this study, a clear signal of the Bragg peak was observed for an energy deposition as low as 10(12) eV. The signal amplitude showed a linear increase with particle number per pulse and thus, dose. Bragg peak position measurements were reproducible within ±30 μm and agreed with Geant4 simulations to better than 100 μm. The ionoacoustic signal pattern allowed for a detailed analysis of the Bragg peak and could be well reproduced by k-WAVE simulations. CONCLUSIONS The authors have studied the ionoacoustic signal of the Bragg peak in experiments using a 20 MeV proton beam with its correspondingly localized energy deposition, demonstrating submillimeter position resolution and providing a deep insight in the correlation between the acoustic signal and Bragg peak shape. These results, together with earlier experiments and new simulations (including the results in this study) at higher energies, suggest ionoacoustics as a technique for range verification in particle therapy at locations, where the tumor can be localized by ultrasound imaging. This acoustic range verification approach could offer the possibility of combining anatomical ultrasound and Bragg peak imaging, but further studies are required for translation of these findings to clinical application.
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Affiliation(s)
- W Assmann
- Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching 85748, Germany
| | - S Kellnberger
- Institute for Biological and Medical Imaging, Technische Universität München and Helmholtz Zentrum München, Ingolstädter Landstrasse 1, Neuherberg 85764, Germany
| | - S Reinhardt
- Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching 85748, Germany
| | - S Lehrack
- Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching 85748, Germany
| | - A Edlich
- Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching 85748, Germany
| | - P G Thirolf
- Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching 85748, Germany
| | - M Moser
- Institute for Applied Physics and Measurement Technology, Universität der Bundeswehr, Werner-Heisenberg-Weg 39, Neubiberg 85577, Germany
| | - G Dollinger
- Institute for Applied Physics and Measurement Technology, Universität der Bundeswehr, Werner-Heisenberg-Weg 39, Neubiberg 85577, Germany
| | - M Omar
- Institute for Biological and Medical Imaging, Technische Universität München and Helmholtz Zentrum München, Ingolstädter Landstrasse 1, Neuherberg 85764, Germany
| | - V Ntziachristos
- Institute for Biological and Medical Imaging, Technische Universität München and Helmholtz Zentrum München, Ingolstädter Landstrasse 1, Neuherberg 85764, Germany
| | - K Parodi
- Department for Medical Physics, Ludwig-Maximilians-Universität München, Am Coulombwall 1, Garching 85748, Germany
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16
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Thirolf PG, Aldawood S, Boehmer M, Bortfeldt J, Castelhano I, Gernhaeuser R, v.d. Kolff H, Lang C, Maier L, Schaart DR, Parodi K. SU-E-J-46: Development of a Compton Camera Prototype for Online Range Verification of Laser-Accelerated Proton Beams. Med Phys 2014. [DOI: 10.1118/1.4888098] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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17
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Minaya Ramirez E, Ackermann D, Blaum K, Block M, Droese C, Düllmann CE, Dworschak M, Eibach M, Eliseev S, Haettner E, Herfurth F, Heßberger FP, Hofmann S, Ketelaer J, Marx G, Mazzocco M, Nesterenko D, Novikov YN, Plaß WR, Rodríguez D, Scheidenberger C, Schweikhard L, Thirolf PG, Weber C. Direct mapping of nuclear shell effects in the heaviest elements. Science 2012; 337:1207-10. [PMID: 22878498 DOI: 10.1126/science.1225636] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Quantum-mechanical shell effects are expected to strongly enhance nuclear binding on an "island of stability" of superheavy elements. The predicted center at proton number Z = 114, 120, or 126 and neutron number N = 184 has been substantiated by the recent synthesis of new elements up to Z = 118. However, the location of the center and the extension of the island of stability remain vague. High-precision mass spectrometry allows the direct measurement of nuclear binding energies and thus the determination of the strength of shell effects. Here, we present such measurements for nobelium and lawrencium isotopes, which also pin down the deformed shell gap at N = 152.
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18
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Haettner E, Ackermann D, Audi G, Blaum K, Block M, Eliseev S, Fleckenstein T, Herfurth F, Hessberger FP, Hofmann S, Ketelaer J, Ketter J, Kluge HJ, Marx G, Mazzocco M, Novikov YN, Plass WR, Rahaman S, Rauscher T, Rodríguez D, Schatz H, Scheidenberger C, Schweikhard L, Sun B, Thirolf PG, Vorobjev G, Wang M, Weber C. Mass measurements of very neutron-deficient Mo and Tc isotopes and their impact on rp process nucleosynthesis. Phys Rev Lett 2011; 106:122501. [PMID: 21517310 DOI: 10.1103/physrevlett.106.122501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Indexed: 05/30/2023]
Abstract
The masses of ten proton-rich nuclides, including the N=Z+1 nuclides ⁸⁵Mo and ⁸⁷Tc, were measured with the Penning trap mass spectrometer SHIPTRAP. Compared to the Atomic Mass Evaluation 2003 a systematic shift of the mass surface by up to 1.6 MeV is observed causing significant abundance changes of the ashes of astrophysical x-ray bursts. Surprisingly low α separation energies for neutron-deficient Mo and Tc are found, making the formation of a ZrNb cycle in the rp process possible. Such a cycle would impose an upper temperature limit for the synthesis of elements beyond Nb in the rp process.
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Affiliation(s)
- E Haettner
- II. Physikalisches Institut, Justus-Liebig-Universität, 35392 Gießen, Germany.
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19
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Wimmer K, Kröll T, Krücken R, Bildstein V, Gernhäuser R, Bastin B, Bree N, Diriken J, Van Duppen P, Huyse M, Patronis N, Vermaelen P, Voulot D, Van de Walle J, Wenander F, Fraile LM, Chapman R, Hadinia B, Orlandi R, Smith JF, Lutter R, Thirolf PG, Labiche M, Blazhev A, Kalkühler M, Reiter P, Seidlitz M, Warr N, Macchiavelli AO, Jeppesen HB, Fiori E, Georgiev G, Schrieder G, Das Gupta S, Lo Bianco G, Nardelli S, Butterworth J, Johansen J, Riisager K. Discovery of the shape coexisting 0+ state in 32 Mg by a two neutron transfer reaction. Phys Rev Lett 2010; 105:252501. [PMID: 21231582 DOI: 10.1103/physrevlett.105.252501] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Indexed: 05/30/2023]
Abstract
The "island of inversion" nucleus 32 Mg has been studied by a (t, p) two neutron transfer reaction in inverse kinematics at REX-ISOLDE. The shape coexistent excited 0+ state in 32 Mg has been identified by the characteristic angular distribution of the protons of the Δ L=0 transfer. The excitation energy of 1058 keV is much lower than predicted by any theoretical model. The low γ-ray intensity observed for the decay of this 0+ state indicates a lifetime of more than 10 ns. Deduced spectroscopic amplitudes are compared with occupation numbers from shell-model calculations.
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Affiliation(s)
- K Wimmer
- Physik Department E12, Technische Universität München, 85748 Garching, Germany
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20
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Block M, Ackermann D, Blaum K, Droese C, Dworschak M, Eliseev S, Fleckenstein T, Haettner E, Herfurth F, Hessberger FP, Hofmann S, Ketelaer J, Ketter J, Kluge HJ, Marx G, Mazzocco M, Novikov YN, Plass WR, Popeko A, Rahaman S, Rodríguez D, Scheidenberger C, Schweikhard L, Thirolf PG, Vorobyev GK, Weber C. Direct mass measurements above uranium bridge the gap to the island of stability. Nature 2010; 463:785-8. [DOI: 10.1038/nature08774] [Citation(s) in RCA: 162] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Accepted: 12/17/2009] [Indexed: 11/09/2022]
Affiliation(s)
- M Block
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt, Germany.
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21
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Schwerdtfeger W, Thirolf PG, Wimmer K, Habs D, Mach H, Rodriguez TR, Bildstein V, Egido JL, Fraile LM, Gernhäuser R, Hertenberger R, Heyde K, Hoff P, Hübel H, Köster U, Kröll T, Krücken R, Lutter R, Morgan T, Ring P. Shape coexistence near neutron number N=20: first identification of the E0 decay from the deformed first excited Jpi=0+ state in 30Mg. Phys Rev Lett 2009; 103:012501. [PMID: 19659139 DOI: 10.1103/physrevlett.103.012501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2008] [Revised: 02/20/2009] [Indexed: 05/28/2023]
Abstract
The 1789 keV state in 30Mg was identified as the first excited 0+ state via its electric monopole (E0) transition to the ground state. The measured small value of rho2(E0,0(2)+-->0(1)+)=(26.2+/-7.5)x10(-3) implies within a two-level model a small mixing of competing configurations with largely different intrinsic quadrupole deformation near the neutron shell closure at N=20. Axially symmetric configuration mixing calculations identify the ground state of 30Mg to be based on neutron configurations below the N=20 shell closure, while the excited 0+ state mainly consists of two neutrons excited into the nu 1f7/2 orbital. The experimental result represents the first case where an E0 back decay from a strongly deformed second to the normal deformed first nuclear potential minimum well has been unambiguously identified, thus directly proving shape coexistence at the borderline of the much-debated "island of inversion."
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Affiliation(s)
- W Schwerdtfeger
- Ludwig-Maximilians-Universität München, D-85748 Garching, Germany
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22
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Rauth C, Ackermann D, Blaum K, Block M, Chaudhuri A, Di Z, Eliseev S, Ferrer R, Habs D, Herfurth F, Hessberger FP, Hofmann S, Kluge HJ, Maero G, Martín A, Marx G, Mukherjee M, Neumayr JB, Plass WR, Rahaman S, Rodríguez D, Scheidenberger C, Schweikhard L, Thirolf PG, Vorobjev G, Weber C. First Penning trap mass measurements beyond the proton drip line. Phys Rev Lett 2008; 100:012501. [PMID: 18232754 DOI: 10.1103/physrevlett.100.012501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 07/19/2007] [Indexed: 05/25/2023]
Abstract
The masses of six neutron-deficient rare holmium and thulium isotopes close to the proton drip line were determined with the SHIPTRAP Penning trap mass spectrometer. For the first time the masses of the proton-unbound isotopes 144,145Ho and 147,148Tm were directly measured. The proton separation energies were derived from the measured mass values and compared to predictions from mass formulas. The new values of the proton separation energies are used to determine the location of the proton drip line for holmium and thulium more accurately.
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Affiliation(s)
- C Rauth
- Gesellschaft für Schwerionenforschung (GSI), Planckstrasse 1, 64291 Darmstadt, Germany
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23
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Wilson AN, Singh AK, Hübel H, Davidson PM, Görgen A, Rossbach D, Korichi A, Astier A, Azaiez F, Bazzacco D, Bourgeois C, Buforn N, Byrne AP, Dracoulis GD, Hannachi F, Hauschild K, Korten W, Kröll T, Lane GJ, Lopez-Martens A, Redon N, Reiter P, Rossi-Alvarez C, Schonwasser G, Stezowski O, Thirolf PG. Excitation energies of superdeformed States in 196Pb: towards a systematic study of the second well in Pb isotopes. Phys Rev Lett 2005; 95:182501. [PMID: 16383897 DOI: 10.1103/physrevlett.95.182501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Indexed: 05/05/2023]
Abstract
The excitation energy of the lowest-energy superdeformed band in 196Pb is established using the techniques of time-correlated gamma-ray spectroscopy. Together with previous measurements on 192Pb and 194Pb, this result allows superdeformed excitation energies, binding energies, and two-proton and two-neutron separation energies to be studied systematically, providing stringent tests for current nuclear models. The results are examined for evidence of a "superdeformed shell gap."
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Affiliation(s)
- A N Wilson
- Department of Nuclear Physics, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia.
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Niedermaier O, Scheit H, Bildstein V, Boie H, Fitting J, von Hahn R, Köck F, Lauer M, Pal UK, Podlech H, Repnow R, Schwalm D, Alvarez C, Ames F, Bollen G, Emhofer S, Habs D, Kester O, Lutter R, Rudolph K, Pasini M, Thirolf PG, Wolf BH, Eberth J, Gersch G, Hess H, Reiter P, Thelen O, Warr N, Weisshaar D, Aksouh F, Van den Bergh P, Van Duppen P, Huyse M, Ivanov O, Mayet P, Van de Walle J, Aystö J, Butler PA, Cederkäll J, Delahaye P, Fynbo HOU, Fraile LM, Forstner O, Franchoo S, Köster U, Nilsson T, Oinonen M, Sieber T, Wenander F, Pantea M, Richter A, Schrieder G, Simon H, Behrens T, Gernhäuser R, Kröll T, Krücken R, Münch M, Davinson T, Gerl J, Huber G, Hurst A, Iwanicki J, Jonson B, Lieb P, Liljeby L, Schempp A, Scherillo A, Schmidt P, Walter G. "Safe" Coulomb excitation of 30Mg. Phys Rev Lett 2005; 94:172501. [PMID: 15904283 DOI: 10.1103/physrevlett.94.172501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2004] [Indexed: 05/02/2023]
Abstract
We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion."
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Affiliation(s)
- O Niedermaier
- Max-Planck-Insitut für Kernphysik, Heidelberg, Germany
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