Measurement of the ^{140}Ce(n,γ) Cross Section at n_TOF and Its Astrophysical Implications for the Chemical Evolution of the Universe

^{140}Ce(n,γ) is a key reaction for slow neutron-capture (s-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty ≈5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.

74 Ge( n , γ ) cross section below 70 keV measured at n_TOF CERN

Neutron capture reaction cross sections on 74 Ge are of importance to determine 74 Ge production during the astrophysical slow neutron capture process. We present new resonance data on 74 Ge( n , γ ) reactions below 70 keV neutron energy. We calculate Maxwellian averaged cross sections, combining our data below 70 keV with evaluated cross sections at higher neutron energies. Our stellar cross sections are in agreement with a previous activation measurement performed at Forschungszentrum Karlsruhe by Marganiec et al., once their data has been re-normalised to account for an update in the reference cross section used in that experiment.

First 80Se(n,γ) cross section measurement with high resolution in the full stellar energy range 1 eV - 100 keV and its astrophysical implications for the s-process

Most elements heavier than iron have been generated in the stellar media by means of neutron capture reactions, approximately half are produced by the slow neutron capture or s-process. Radiative neutron capture cross section measurements are of fundamental importance for the study of this mechanism. In this contribution we present a brief summary on the measurement and results for the 80Se(n,γ) cross-section. The experiment was carried out at CERN n_TOF EAR1 via the time of flight (ToF) technique, using four C6D6 scintillation detectors with very fast response. More than a hundred new resonances have been analyzed for the first time with a high accuracy. The MACS obtained at kT = 8 keV is 36% smaller than the recommended value in KADo-NiS. Some of the astrophysical implications of this result are elucidated in this contribution.

Compton Imaging and Machine-Learning techniques for an enhanced sensitivity in key stellar (n,γ) measurements

Neutron capture cross-section measurements are fundamental in the study of astrophysical phenomena, such as the slow neutron capture (s-) process of nucleosynthesis operating in red-giant stars. To enhance the sensitivity of such measurements we have developed the i-TED detector. i-TED is an innovative detection system which exploits the Compton imaging technique with the aim of obtaining information about the incoming direction of the detected γ-rays. The imaging capability allows one to reject a large fraction of the dominant γ-ray background, hence enhancing the (n,γ) detection sensitivity.

This work summarizes the main results of the first experimental proof-of-concept of the background rejection with i-TED carried out at CERN n_TOF using an early i-TED demonstrator. Two state-of-the-art C6D6 detectors were also used to benchmark the performance of i-TED. The i-TED prototype built for this study shows a factor of ~3 higher detection sensitivity than C6D6 detectors in the ~10 keV neutron-energy range of astrophysical interest. This works also introduces the perspectives of further enhancement in performance attainable with the final i-TED array and new analysis methodologies based on Machine-Learning techniques. The latter provide higher (n,γ) detection efficiency and similar enhancement in the sensitivity than the analytical method based on the Compton scattering law. Finally, we present our proposal to use this detection system for the first time on key astrophysical (n,γ) measurements, in particular on the s-process branching-point 79Se, which is especially well suited to constrain the thermal conditions of Red Giant and Massive Stars.

Double check discharge planning to improve the results of a heart failure programme

Background

Reduction of readmissions in heart failure (HF) patients is a main goal of HF programmes. Establishing a discharge planning for the patient and coordinating it with primary care teams are key aspects for their success.

Purpose

Evaluate whether a double check discharge planning based on adding face-to-face joint weekly sessions with primary care managers to the conventional electronic communication of care plan reduces 6-month readmission and 6-month mortality.

Methods

We evaluated all patients discharged from hospital with HF as primary diagnosis between September 2017 and January 2019. We compared outcomes between patients discharged during Period #1 (single check; September 2017 - April 2018) and those discharged during Period #2 (double check; May 2018 - January 2019).

Primary endpoint was the combined endpoint of all-cause death or all-cause hospitalization 6 months after discharge from the index hospitalization.

Results

The study enrolled 317 patients: 182 in Period #1 and 135 in Period #2.

Mean age was 76±9 years. There was a higher proportion of patients with diabetes and COPD in Period #1, with no differences in other baseline characteristics.

The combined endpoint of all cause-death and all-cause hospitalization at 6 months was significantly reduced in patients in the double check discharge planning group (27% vs. 16%, p 0.021).

Conclusions

In a HF programme, the addition of a double check discharge planning based on having joint weekly sessions with primary care managers on top of the conventional electronic communication of care plan reduces 6-month readmission and 6-month mortality.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): Hospital Universitari de Bellvitge

Psychosocial and clinical factors associated with poor self-care in patients with chronic heart failure

Background

Self care is a crucial factor in the education of patients with heart failure (HF) and directly impacts in the progression of the disease.

Beyond heart failure related factors, the role of psychosocial determinants and its interaction with clinical aspects has not been fully explored.

Aims

The aim of the study was to analyze both clinical and psychosocial factors associated with poor self care in patients with chronic HF.

Methods

Self care was evaluated at baseline with the 9 item European HFR Self Care Behaviour Scale (9 item ESCBS).

Scores were standardized and reversed from 0 (worst self care) to 100 (better self care). This study we analysed the associations between poor self care (defined as scores in the lower tertile of the 9 item ESCBS) with demographic, HF-related (clinical) and psychosocial factors in all patients at baseline.

Results

We included 1123 patients: mean age 72±11, 639 (60%) were male, mean LVEF 45±17 and 454 (40%) were in NYHA class III or IV. Mean score of the 9-item ESCBS was 69±28. In the clinical multivariate analyses HF-related factors associated with poor self-care were serum albumins level, ckd level and previous admission due to heart failure. In the psychosocial multivariate analyses poor social support, depressive symptoms and needing a caregiver were independently associated with poor self care. In combined models, only psychosocial factors were independently associated with poor self care whereas no clinical factors remain in the model.

Conclusion

Our study showed that psychosocial conditions are the main factors independently associated with poor self-care in patients with chronic heart failure

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): Hospital del Bellvitge

Association between self-care and prognosis in 1123 patients with chronic heart failure

Background

Self-care is a crucial factor in the education of patients with heart failure (HF) and directly impacts in the progression of the disease. However, little is published about its major clinical implications as admission or mortality in patients with HF.

Aims and methods

The aim of the study was to analyze time to admission due to acute heart failure and mortality associated with poor self-care in patients with chronic HF.

We prospectively recruited consecutive patients with stable chronic HF referred to a nurse-led HF programme. Selfcare was evaluated at baseline with the 9 item European Heart Failure Self-Care Behavior Scale. Scores were standardized and reversed from 0 (worst selfcare) to 100 (better self care). For the purpose of this study we analyzed the associations of worse self-care (defined as scores below the lower tertile of the scale) with demographic, disease-related (clinical) and psychosocial factors in all patients at baseline.

Results

We included 1123 patients, mean age 72±11, 639 (60%) were male, mean LVEF 45±17 and 454 (40,4%) were in NYHA class III or IV. Mean score of the 9-item ESCBE was 69±28. Score below 55 (lower tertile) defined impaired selfcare behaviour.

Those patients with worse self-care had more ischaemic heart disease, more COPD, and they achieved less distance in the 6 minute walking test. Regarding psychosocial items patients in lower tertile of self-care needed a caregiver more frequently, they present more cognitive impairment, depressive symptoms and worse score in terms of health self-perception.

Multivariate Cox Models showed that a score below 55 points in 9-item ESCBE was independently associated with higher readmission due to acute heart failure [HR 1.26 (1.02–1.57), p value=0.034] and with mortality [HR 1.24 CI95% (1.02–1.50), p value=0.028]

Conclusion

Poor self-care measured with the modified 9-item ESCBE was associated with higher risk of admission due to acute decompensation and higher risk of mortality in patients with chronic heart failure.

These results highlight the importance of assessing self-care and provide measures to improve them.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): Hospital Univesitario de Bellvitge

Long-term effectiveness of a nurse-led 7-step transitional intervention programme in heart failure

Background

Reduction of 30-day readmission in heart failure (HF) patients is a main goal of health-care systems. Programmes to decrease 30-day readmission have successfully reduced it but have failed to neither maintain benefit afterwards nor decrease mortality. Moreover, in many cases the price of reducing 30-day readmission is a mortality increase.

Purpose

Evaluate whether the impact of a fully nurse-led HF programme directed to reduce 30-day readmission and mortality extends to longer periods of time, including 90 days and 180 days after discharge.

Methods

We evaluated all patients discharged from hospital with HF as primary diagnosis between January 2017 and January 2019. We compared outcomes between patients discharged during Period #1 (pre-programme; Jan 2017 - Aug 2017) and those discharged during Period #2 (HF programme; Sept 2017 - Jan 2019).

Primary endpoint was the combined endpoint of all-cause death or all-cause hospitalization 90 days and 180 days after discharge from the index hospitalization.

Results

The study enrolled 440 patients: 123 in Period #1 and 317 in Period #2.

Mean age was 75±9 years. There was a higher proportion of female patients in Period #2 (38.2% vs 26.8%, p=0.025), with no differences in other baseline characteristics.

The combined endpoint of all cause-death and all-cause hospitalization was significantly reduced in patients in the HF programme group, both at 90 days [OR 0.37 (0.22–0.63), p<0.001] and at 180 days [OR 0.27 (CI 0.17–0.43), p<0.001]. Such a decrease was at expense of a reduction in cardiovascular (CV) hospitalization and HF hospitalization.

There were no differences between groups in mortality [OR 0.96 (0.18–5.00), p=0.293].

Conclusions

A fully nurse-led HF programme reduces the combined endpoint of all-cause death and all-cause hospitalization both at 90 days and 180 days after an index discharge for HF.

Such a decrease is driven by a reduction of CV and HF hospitalization, which are maintained over time. There were no differences between groups in mortality.

Funding Acknowledgement

Type of funding source: Public hospital(s). Main funding source(s): Hospital Universitari de Bellvitge

Implication of heat shock proteins in rotavirus entry into Reh cells

The mechanisms of rotavirus entry into the target cell are described as a multi-step event in which the virions are bound to sialic acid (SA), followed by interaction with heat shock cognate protein 70 (Hsc70), some integrins and protein disulfide isomerase (PDI). However, the cell surface receptor molecules facilitating the entry of tumor cell-adapted rotavirus are not completely characterized. Using infection blocking assays with antibodies to some heat shock proteins (HSPs) and also some inhibitors of these cellular proteins, we were able to identify the cell surface Hsp90, Hsp70, Hsc70, Hsp60, Hsp40, PDI and integrin β3 as receptors of tumor cell-adapted rotavirus in Reh cells. Furthermore, the results also indicated that these rotavirus receptors are associated with lipid microdomains (rafts). Our findings provide evidence that rotavirus tropism for these human acute lymphocytic leukemia cells is explained by the relatively high expression of some HSPs in rafts. The results shown here encourage further research aim at evaluating the potential use of rotaviruses as an oncolytic agent for the treatment of some cancers. Keywords: heat shock proteins; rotavirus; cell receptor; cancer; oncolytic virus.

Neutron Capture on the s-Process Branching Point ^{171}Tm via Time-of-Flight and Activation

The neutron capture cross sections of several unstable nuclides acting as branching points in the s process are crucial for stellar nucleosynthesis studies. The unstable ^{171}Tm (t_{1/2}=1.92  yr) is part of the branching around mass A∼170 but its neutron capture cross section as a function of the neutron energy is not known to date. In this work, following the production for the first time of more than 5 mg of ^{171}Tm at the high-flux reactor Institut Laue-Langevin in France, a sample was produced at the Paul Scherrer Institute in Switzerland. Two complementary experiments were carried out at the neutron time-of-flight facility (n_TOF) at CERN in Switzerland and at the SARAF liquid lithium target facility at Soreq Nuclear Research Center in Israel by time of flight and activation, respectively. The result of the time-of-flight experiment consists of the first ever set of resonance parameters and the corresponding average resonance parameters, allowing us to make an estimation of the Maxwellian-averaged cross sections (MACS) by extrapolation. The activation measurement provides a direct and more precise measurement of the MACS at 30 keV: 384(40) mb, with which the estimation from the n_TOF data agree at the limit of 1 standard deviation. This value is 2.6 times lower than the JEFF-3.3 and ENDF/B-VIII evaluations, 25% lower than that of the Bao et al. compilation, and 1.6 times larger than the value recommended in the KADoNiS (v1) database, based on the only previous experiment. Our result affects the nucleosynthesis at the A∼170 branching, namely, the ^{171}Yb abundance increases in the material lost by asymptotic giant branch stars, providing a better match to the available pre-solar SiC grain measurements compared to the calculations based on the current JEFF-3.3 model-based evaluation.

Production yields of 𝛽+ emitters for range verification in proton therapy

In-vivo Positron Emission Tomography (PET) range verification relies on the comparison of the measured and estimated activity distributions from β+ emitters induced by the proton beam on the most abundant elements in the human body, right after (looking at the long-lived β+ emitters 11C, 13N and 15O) or during (looking at the short-lived β+ emitters 29P, 12N, 38mK and 10C) the irradiation. The accuracy of the estimated activity distributions is basically that of the underlying cross section data. In this context, the aim of this work is to improve the knowledge of the production yields of β+ emitters of interest in proton therapy. In order to measure the long-lived β+ isotopes, a new method has been developed combining the multi-foil technique with the measurement of the induced activity with a clinical PET scanner. This technique has been tested successfully below 18 MeV at CNA (Spain) and will be used at a clinical beam to obtain data up to 230 MeV. However, such method does not allow measuring the production short-lived isotopes (lower half-life). For this, the proposed method combines a series of targets sandwiched between aluminum foils (acting as both degraders and converters) placed between two LaBr3 detectors that will measure the pairs of 511 keV γ-rays. The first tests will take place at the AGOR facility at KVI-CART, in Groningen.

Setup for the measurement of the 235U(n, f) cross section relative to n-p scattering up to 1 GeV

The neutron induced fission of 235U is extensively used as a reference for neutron fluence measurements in various applications, ranging from the investigation of the biological effectiveness of high energy neutrons, to the measurement of high energy neutron cross sections of relevance for accelerator driven nuclear systems. Despite its widespread use, no data exist on neutron induced fission of 235U above 200 MeV. The neutron facility n_TOF offers the possibility to improve the situation. The measurement of 235U(n,f) relative to the differential n-p scattering cross-section, was carried out in September 2018 with the aim of providing accurate and precise cross section data in the energy range from 10 MeV up to 1 GeV. In such measurements, Recoil Proton Telescopes (RPTs) are used to measure the neutron flux while the fission events are detected and counted with dedicated detectors. In this paper the measurement campaign and the experimental set-up are illustrated.

Monte Carlo simulations and n-p differential scattering data measured with Proton Recoil Telescopes

The neutron-induced fission cross section of 235U, a standard at thermal energy and between 0.15 MeV and 200 MeV, plays a crucial role in nuclear technology applications. The long-standing need of improving cross section data above 20 MeV and the lack of experimental data above 200 MeV motivated a new experimental campaign at the n_TOF facility at CERN. The measurement has been performed in 2018 at the experimental area 1 (EAR1), located at 185 m from the neutron-producing target (the experiment is presented by A. Manna et al. in a contribution to this conference). The 235U(n,f) cross section from 20 MeV up to about 1 GeV has been measured relative to the 1H(n,n)1H reaction, which is considered the primary reference in this energy region. The neutron flux impinging on the 235U sample (a key quantity for determining the fission events) has been obtained by detecting recoil protons originating from n-p scattering in a C2H4 sample. Two Proton Recoil Telescopes (PRT), consisting of several layers of solid-state detectors and fast plastic scintillators, have been located at proton scattering angles of 25.07° and 20.32°, out of the neutron beam. The PRTs exploit the ΔE-E technique for particle identification, a basic requirement for the rejection of charged particles from neutron-induced reactions in carbon. Extensive Monte Carlo simulations were performed to characterize proton transport through the different slabs of silicon and scintillation detectors, to optimize the experimental set-up and to deduce the efficiency of the whole PRT detector. In this work we compare measured data collected with the PRTs with a full Monte Carlo simulation based on the Geant-4 toolkit.

Characterization and validation of olive FAD and SAD gene families: expression analysis in different tissues and during fruit development

Stearoyl-ACP desaturases (SADs) and fatty acid desaturases (FADs) play a critical role in plant lipid metabolism and also affect oil fatty acid composition introducing double bonds into the hydrocarbon chains to produce unsaturated fatty acids. In the present study, the genomic sequences of three SAD and three FAD candidate genes were characterized in olive and their expression was evaluated in different plant tissues. OeSAD genes corresponded to olive SAD1 and SAD2 and to a newly identified OeSAD4, sharing the conserved protein structure with other plant species. On the other hand, the full-length genomic sequences of two microsomal OeFAD genes (FAD2-1 and FAD2-2) and the plastidial FAD6, were released. When the level of expression was tested on different tissues of cv. Leccino, OeSAD1 and OeSAD2 were mainly expressed in the fruits, while OeFAD genes showed the lowest expression in this tissue. The mRNA profiling of all genes was directly studied in fruits of Leccino and Coratina cultivars during fruit development. In both genotypes, the expression level of OeSAD1 and OeSAD2 had the highest value during and after the pit-hardening period, when oil accumulation in fruit mesocarp is intensively increasing. Furthermore, the expression level of both OeFAD2 genes, which were the main candidates for oleic acid desaturation, were almost negligible during fruit ripening. These results have made possible to define candidate genes of the machinery regulation of fatty acid composition in olive oil, providing information on their sequence, gene structure and chromosomal location.

Measurement and analysis of 155,157Gd(n,γ) from thermal energy to 1 keV

We have measured the capture cross section of the 155Gd and 157Gd isotopes between 0.025 eV and 1 keV. The capture events were recorded by an array of 4 C6D6 detectors, and the capture yield was deduced exploiting the total energy detection system in combination with the Pulse Height Weighting Techniques. Because of the large cross section around thermal neutron energy, 4 metallic samples of different thickness were used to prevent problems related to self-shielding. The samples were isotopically enriched, with a cross contamination of the other isotope of less than 1.14%. The capture yield was analyzed with an R-Matrix code to describe the cross section in terms of resonance parameters. Near thermal energies, the results are significantly different from evaluations and from previous time-of-flight experiments. The data from the present measurement at n_TOF are publicly available in the experimental nuclear reaction database EXFOR.

Measurement of the energy-differential cross-section of the 12C(n,p)12B and 12C(n,d)11B reactions at the n_TOF facility at CERN

Although the 12C(n,p)12B and 12C(n,d)11B reactions are of interest in several fields of basic and applied Nuclear Physics the present knowledge of these two cross-sections is far from being accurate and reliable, with both evaluations and data showing sizable discrepancies. As part of the challenging n_TOF program on (n,cp) nuclear reactions study, the energy differential cross-sections of the 12C(n,p)12B and 12C(n,d)11 B reactions have been measured at CERN from the reaction thresholds up to 30 MeV neutron energy. Both measurements have been recently performed at the long flight-path (185 m) experimental area of the n_TOF facility at CERN using a pure (99.95%) rigid graphite target and two silicon telescopes. In this paper an overview of the experiment is presented together with a few preliminary results.

Preliminary results on the 233U α-ratio measurement at n_TOF

233U is the fissile nuclei in the Th-U fuel cycle with a particularily small neutron capture cross setion which is on average about one order of magnitude lower than its fission cross section. Hence, the measurement of the 233U(n, γ) cross section relies on a method to accurately distinguish between capture and fission γ-rays. A measurement of the 233U α-ratio has been performed at the n_TOF facility at CERN using a so-called fission tagging setup, coupling n_TOF 's Total Absorption Calorimeter with a novel fission chamber to tag the fission γ-rays. The experimental setup is described and essential parts of the analysis are discussed. Finally, a preliminary 233U α-ratio is presented.

Status and perspectives of the neutron time-of-flight facility n_TOF at CERN

Since the start of its operation in 2001, based on an idea of Prof. Carlo Rubbia [1], the neutron time of-flight facility of CERN, n_TOF, has become one of the most forefront neutron facilities in the world for wide-energy spectrum neutron cross section measurements. Thanks to the combination of excellent neutron energy resolution and high instantaneous neutron flux available in the two experimental areas, the second of which has been constructed in 2014, n_TOF is providing a wealth of new data on neutron-induced reactions of interest for nuclear astrophysics, advanced nuclear technologies and medical applications. The unique features of the facility will continue to be exploited in the future, to perform challenging new measurements addressing the still open issues and long-standing quests in the field of neutron physics. In this document the main characteristics of the n_TOF facility and their relevance for neutron studies in the different areas of research will be outlined, addressing the possible future contribution of n_TOF in the fields of nuclear astrophysics, nuclear technologies and medical applications. In addition, the future perspectives of the facility will be described including the upgrade of the spallation target, the setup of an imaging installation and the construction of a new irradiation area.

Neutron capture cross section measurements of 241Am at the n_TOF facility

Neutron capture on 241Am plays an important role in the nuclear energy production and also provides valuable information for the improvement of nuclear models and the statistical interpretation of the nuclear properties. A new experiment to measure the 241Am(n, γ) cross section in the thermal region and the first few resonances below 10 eV has been carried out at EAR2 of the n_TOF facility at CERN. Three neutron-insensitive C6D6 detectors have been used to measure the neutron-capture gamma cascade as a function of the neutron time of flight, and then deduce the neutron capture yield. Preliminary results will be presented and compared with previously obtained results at the same facility in EAR1. In EAR1 the gamma-ray background at thermal energies was about 90% of the signal while in EAR2 is up to a 25 factor much more favorable signal to noise ratio. We also extended the low energy limit down to subthermal energies. This measurement will allow a comparison with neutron capture measurements conducted at reactors and using a different experimental technique.

Study of the neutron-induced fission cross section of 237Np at CERN's n_TOF facility over a wide energy range

Neutron-induced fission cross sections of isotopes involved in the nuclear fuel cycle are vital for the design and safe operation of advanced nuclear systems. Such experimental data can also provide additional constraints for the adjustment of nuclear model parameters used in the evaluation process, resulting in the further development of fission models. In the present work, the 237Np(n,f) cross section was studied at the EAR2 vertical beam-line at CERN's n_TOF facility, over a wide range of neutron energies, from meV to MeV, using the time-of-flight technique and a set-up based on Micromegas detectors, in an attempt to provide accurate experimental data. Preliminary results in the 200 keV – 14 MeV neutron energy range as well as the experimental procedure, including a description of the facility and the data handling and analysis, will be presented.

Study of photon strength functions of241Pu and245Cm from neutron capture measurements

We have measured theγ-rays following neutron capture on240Pu and244Cm at the n_TOF facility at CERN with the Total Absorption Calorimeter (TAC) and with C6D6 organic scintillators. The TAC is made of 40 BaF2 crystals operating in coincidence and covering almost the entire solid angle. This allows to obtain information concerning the energy spectra and the multiplicity of the measured captureγ-ray cascades. Additional information is also obtained from the C6D6 detectors. We have analyzed the measured data in order to draw conclusions about the Photon Strength Functions (PSFs) of241Pu and245Cm below their neutron separation energies. The analysis has been performed by fitting the PSFs to the experimental results, using the differential evolution method, in order to find neutron capture cascades capable of reproducing at the same time a great variety of deposited energy spectra.

Accurate measurement of the standard 235U(n,f) cross section from thermal to 170 keV neutron energy

An accurate measurement of the 235U(n,f) cross section from thermal to 170 keV of neutron energy has recently been performed at n_TOF facility at CERN using 6Li(n,t)4He and 10B(n,α)7Li as references. This measurement has been carried out in order to investigate a possible overestimation of the 235U fission cross section evaluation provided by most recent libraries between 10 and 30 keV. A custom experimental apparatus based on in-beam silicon detectors has been used, and a Monte Carlo simulation in GEANT4 has been employed to characterize the setup and calculate detectors efficiency. The results evidenced the presence of an overestimation in the interval between 9 and 18 keV and the new data may be used to decrease the uncertainty of 235U(n,f) cross section in the keV region.

First results of the 230Th(n,f) cross section measurements at the CERN n_TOF facility

The study of neutron-induced reactions on actinides is of considerable importance for the design of advanced nuclear systems and alternative fuel cycles. Specifically, 230Th is produced from the α-decay of 234U as a byproduct of the 232Th/233U fuel cycle, thus the accurate knowledge of its fission cross section is strongly required. However, few experimental datasets exist in literature with large deviations among them, covering the energy range between 0.2 to 25 MeV. In addition, the study of the 230Th(n,f) cross-section is of great interest in the research on the fission process related to the structure of the fission barriers. Previous measurements have revealed a large resonance at En=715 keV and additional fine structures, but with high discrepancies among the cross-section values of these measurements. This contribution presents preliminary results of the 230Th(n,f) cross-section measurements at the CERN n_TOF facility. The high purity targets of the natural, but very rare isotope 230Th, were produced at JRC-Geel in Belgium. The measurements were performed at both experimental areas (EAR-1 and EAR-2) of the n_TOF facility, covering a very broad energy range from thermal up to at least 100 MeV. The experimental setup was based on Micromegas detectors with the 235U(n,f) and 238U(n,f) reaction cross-sections used as reference.

Laser-driven neutrons for time-of-flight experiments?

Neutron beams, both pulsed and continuous, are a powerful tool in a wide variety of research fields and applications. Nowadays, pulsed neutron beams are produced in conventional accelerator facilities in which the time-of-fight technique is used to determine the kinetic energy of the neutrons inducing the reactions of interest.

In the last decades, the development of ultra-short (femtosecond) and ultra-high power (> 1018 W/cm2) lasers has opened the door to a vast number of new applications, including the production and acceleration of pulsed ion beams. These have been recently used to produce pulsed neutron beams, reaching fluxes per pulse similar and even higher than those of conventional neutron beams, hence becoming an alternative for the pulsed neutron beam users community. Nevertheless, these laser-driven neutrons have not been exploited in nuclear physics experiments so far.

Our main goal is to produce and characterize laser-driven neutrons but optimizing the analysis, diagnostic and detection techniques currently used in conventional neutron sources to implement them in this new environment. As a result, we would lay down the viability of carrying out nuclear physics experiments using this kind of sources by identifying the advantages and limitations of this production method.

To achieve this purpose, we plan to perform experiments in both medium (50TW@L2A2, in Santiago de Com-postela) and high (1PW@APOLLON, in Paris) power laser facilities.

New reaction rates for the destruction of7Be during big bang nucleosynthesis measured at CERN/n_TOF and their implications on the cosmological lithium problem

New measurements of the7Be(n,α)4He and7Be(n,p)7Li reaction cross sections from thermal to keV neutron energies have been recently performed at CERN/n_TOF. Based on the new experimental results, astrophysical reaction rates have been derived for both reactions, including a proper evaluation of their uncertainties in the thermal energy range of interest for big bang nucleosynthesis studies. The new estimate of the7Be destruction rate, based on these new results, yields a decrease of the predicted cosmological7Li abundance insufficient to provide a viable solution to the cosmological lithium problem.

The 154Gd neutron capture cross section measured at the n_TOF facility and its astrophysical implications

The (n, γ) cross sections of the gadolinium isotopes play an important role in the study of the stellar nucleosynthesis. In particular, among the isotopes heavier than Fe, 154Gd together with 152Gd have the peculiarity to be mainly produced by the slow capture process, the so-called s-process, since they are shielded against the β-decay chains from the r-process region by their stable samarium isobars. Such a quasi pure s-process origin makes them crucial for testing the robustness of stellar models in galactic chemical evolution (GCE). According to recent models, the 154Gd and 152Gd abundances are expected to be 15-20% lower than the reference un-branched s-process 150Sm isotope. The close correlation between stellar abundances and neutron capture cross sections prompted for an accurate measurement of 154Gd cross section in order to reduce the uncertainty attributable to nuclear physics input and eventually rule out one of the possible causes of present discrepancies between observation and model predictions. To this end, the neutron capture cross section of 154Gd was measured in a wide neutron energy range (from thermal up to some keV) with high resolution in the first experimental area of the neutron time-of-flight facility n_TOF (EAR1) at CERN. In this contribution, after a brief description of the motivation and of the experimental setup used in the measurement, the preliminary results of the 154Gd neutron capture reaction as well as their astrophysical implications are presented.

Measurement of the 242Pu(n, γ) cross section from thermal to 500 keV at the Budapest research reactor and CERN n_TOF-EAR1 facilities

The design and operation of innovative nuclear systems requires a better knowledge of the capture and fission cross sections of the Pu isotopes. For the case of capture on 242Pu, a reduction of the uncertainty in the fast region down to 8-12% is required. Moreover, aiming at improving the evaluation of the fast energy range in terms of average parameters, the OECD NEA High Priority Request List (HPRL) requests high-resolution capture measurements with improved accuracy below 2 keV. The current uncertainties also affect the thermal point, where previous experiments deviate from each other by 20%. A fruitful collaboration betwen JGU Mainz and HZ Dresden-Rossendorf within the EC CHANDA project resulted in a 242Pu sample consisting of a stack of seven fission-like targets making a total of 95(4) mg of 242Pu electrodeposited on thin (11.5 μm) aluminum backings. This contribution presents the results of a set of measurements of the 242Pu(n, γ) cross section from thermal to 500 keV combining different neutron beams and techniques. The thermal point was determined at the Budapest Research Reactor by means of Neutron Activation Analysis and Prompt Gamma Analysis, and the resolved (1 eV - 4 keV) and unresolved (1 - 500 keV) resonance regions were measured using a set of four Total Energy detectors at the CERN n_TOF-EAR1.

Measurement of the244Cm capture cross sections at both CERN n_TOF experimental areas

Accurate neutron capture cross section data for minor actinides (MAs) are required to estimate the production and transmutation rates of MAs in light water reactors with a high burnup, critical fast reactors like Gen-IV systems and other innovative reactor systems such as accelerator driven systems (ADS). Capture reactions of244Cm open the path for the formation of heavier Cm isotopes and of heavier elements such as Bk and Cf. In addition,244Cm shares nearly 50% of the total actinide decay heat in irradiated reactor fuels with a high burnup, even after three years of cooling.

Experimental data for this isotope are very scarce due to the difficulties of providing isotopically enriched samples and because the high intrinsic activity of the samples requires the use of neutron facilities with high instantaneous flux. The only two previous experimental data sets for this neutron capture cross section have been obtained in 1969 using a nuclear explosion and, more recently, at J-PARC in 2010. The neutron capture cross sections have been measured at n_TOF with the same samples that the previous experiments in J-PARC. The samples were measured at n_TOF Experimental Area 2 (EAR-2) with three C6D6detectors and also in Experimental Area 1 (EAR-1) with the Total Absorption Calorimeter (TAC). Preliminary results assessing the quality and limitations of these new experimental datasets are presented for the experiments in both areas. Preliminary yields of both measurements will be compared with evaluated libraries for the first time.

First results of the 241Am(n,f) cross section measurement at the Experimental Area 2 of the n_TOF facility at CERN

Feasibility, design and sensitivity studies on innovative nuclear reactors that could address the issue of nuclear waste transmutation using fuels enriched in minor actinides, require high accuracy cross section data for a variety of neutron-induced reactions from thermal energies to several tens of MeV. The isotope 241Am (T1/2= 433 years) is present in high-level nuclear waste (HLW), representing about 1.8 % of the actinide mass in spent PWR UOx fuel. Its importance increases with cooling time due to additional production from the β-decay of 241Pu with a half-life of 14.3 years. The production rate of 241 Am in conventional reactors, including its further accumulation through the decay of 241Pu and its destruction through transmutation/incineration are very important parameters for the design of any recycling solution. In the present work, the 241 Am(n,f) reaction cross-section was measured using Micromegas detectors at the Experimental Area 2 of the n_TOF facility at CERN. For the measurement, the 235U(n,f) and 238U(n,f) reference reactions were used for the determination of the neutron flux. In the present work an overview of the experimental setup and the adopted data analysis techniques is given along with preliminary results.

Trained dogs can identify malignant solitary pulmonary nodules in exhaled gas

OBJECTIVES

To investigate the capacity of a trained dog to identify LC in patients with malignant SPN.

METHODS

We collected 90 exhaled gas samples from 30 patients with SPN (3 samples/patient). As controls we used 61 healthy volunteers and 18 COPD patients without SNP or LC, in each of whom we collected 5 exhaled gas samples (n = 395). The dog (Blat, a 4-year-old crossbreed between a Labrador Retriever and a Pitbull) and the methodology used were the same as previously reported by our group (see: https://drive.google.com/open?id=1R4mOtOtuZkTeb5iOEEv0K9r2kHKlPhWd).

RESULTS

Of 30 patients with SPN, Blat recognized 27 of them as positive for LC and 3 as negative for LC. These results fully matched post-surgical pathological results. Sensibility was 0.97, Specificity 0.99, Positive Predictive value 0.97 and negative predictive value 0.99. The AUC of the ROC curve was 0.985.

CONCLUSIONS

Trained dogs can identify accurately the malignant origin of SPN. It is now time to develop technology that can match canine olfaction and facilitate the implementation of this diagnostic approach in the clinic.

Preliminary results on the 233U capture cross section and alpha ratio measured at n_TOF (CERN) with the fission tagging technique

233U is of key importance among the fissile nuclei in the Th-U fuel cycle. A particularity of 233U is its small neutron capture cross-section, which is on average about one order of magnitude lower than the fission cross-section. The accuracy in the measurement of the 233U capture cross-section depends crucially on an efficient capture-fission discrimination, thus a combined set-up of fission and γ-detectors is needed. A measurement of the 233U capture cross-section and capture-to-fission ratio was performed at the CERN n_TOF facility. The Total Absorption Calorimeter (TAC) of n_TOF was employed as γ-detector coupled with a novel compact ionization chamber as fission detector. A brief description of the experimental set-up will be given, and essential parts of the analysis procedure as well as the preliminary response of the set-up to capture are presented and discussed.

Fission program at n_TOF

Since its start in 2001 the n_TOF collaboration developed a measurement program on fission, in view of advanced fuels in new generation reactors. A special effort was made on measurement of cross sections of actinides, exploiting the peculiarity of the n_TOF neutron beam which spans a huge energy domain, from the thermal region up to GeV. Moreover fission fragment angular distributions have also been measured. An overview of the cross section results achieved with different detectors is presented, including a discussion of the 237Np case where discrepancies showed up between different detector systems. The results on the anisotropy of the fission fragments and its implication on the mechanism of neutron absorption, and in applications, are also shown.

Study of the photon strength functions and level density in the gamma decay of the n + 234U reaction

The accurate calculations of neutron-induced reaction cross sections are relevant for many nuclear applications. The photon strength functions and nuclear level densities are essential inputs for such calculations. These quantities for 235U are studied using the measurement of the gamma de-excitation cascades in radiative capture on 234U with the Total Absorption Calorimeter at n_TOF at CERN. This segmented 4π gamma calorimeter is designed to detect gamma rays emitted from the nucleus with high efficiency. This experiment provides information on gamma multiplicity and gamma spectra that can be compared with numerical simulations. The code DICEBOXC is used to simulate the gamma cascades while GEANT4 is used for the simulation of the interaction of these gammas with the TAC materials. Available models and their parameters are being tested using the present data. Some preliminary results of this ongoing study are presented and discussed.

Measurement of the 244Cm and 246Cm neutron-induced capture cross sections at the n_TOF facility

The neutron capture reactions of the 244Cm and 246Cm isotopes open the path for the formation of heavier Cm isotopes and heavier elements such as Bk and Cf in a nuclear reactor. In addition, both isotopes belong to the minor actinides with a large contribution to the decay heat and to the neutron emission in irradiated fuels. There are only two previous 244Cm and 246Cm capture cross section measurements: one in 1969 using a nuclear explosion [1] and the most recent data measured at J-PARC in 2010 [2]. The data for both isotopes are very scarce due to the difficulties in performing the measurements: high intrinsic activity of the samples and limited facilities capable of providing isotopically enriched samples.

We have measured both neutron capture cross sections at the n_TOF Experimental Area 2 (EAR-2) with three C6 D6 detectors and also at Area 1 (EAR-1) with the TAC. Preliminary results assessing the quality and limitations (back-ground subtraction, measurement technique and counting statistics) of this new experimental datasets are presented and discussed.

^{7}Be(n,p)^{7}Li Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN

We report on the measurement of the ^{7}Be(n,p)^{7}Li cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n_TOF facility at CERN. This reaction plays a key role in the lithium yield of the big bang nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and they showed a large discrepancy between each other. The measurement was performed with a Si telescope and a high-purity sample produced by implantation of a ^{7}Be ion beam at the ISOLDE facility at CERN. While a significantly higher cross section is found at low energy, relative to current evaluations, in the region of BBN interest, the present results are consistent with the values inferred from the time-reversal ^{7}Li(p,n)^{7}Be reaction, thus yielding only a relatively minor improvement on the so-called cosmological lithium problem. The relevance of these results on the near-threshold neutron production in the p+^{7}Li reaction is also discussed.

Measurement of the radiative capture cross section of the s-process branching points 204Tl and 171Tm at the n_TOF facility (CERN)

The neutron capture cross section of some unstable nuclei is especially relevant for s-process nucleosynthesis studies. This magnitude is crucial to determine the local abundance pattern, which can yield valuable information of the s-process stellar environment. In this work we describe the neutron capture (n,γ) measurement on two of these nuclei of interest, 204Tl and 171Tm, from target production to the final measurement, performed successfully at the n_TOF facility at CERN in 2014 and 2015. Preliminary results on the ongoing experimental data analysis will also be shown. These results include the first ever experimental observation of capture resonances for these two nuclei.

First Measurement of 72Ge(n, γ) at n_TOF

The slow neutron capture process (s-process) is responsible for producing about half of the elemental abundances heavier than iron in the universe. Neutron capture cross sections on stable isotopes are a key nuclear physics input for s-process studies. The 72Ge(n, γ) cross section has an important influence on production of isotopes between Ge and Zr during s-process in massive stars and therefore experimental data are urgently required. 72Ge(n, γ) was measured at the neutron time-of-flight facility n_TOF (CERN) for the first time at stellar energies. The measurement was performed using an enriched 72GeO2 sample at a flight path of 185m with a set of liquid scintillation detectors (C6D6). The motivation, experiment and current status of the data analysis are reported.

Measuring neutron capture rates on ILL-produced unstable isotopes (147Pm, 171Tm and 204Tl, and plans for 79Se and 163Ho) for nucleosynthesis studies

Neutron capture cross sections are among the main inputs for nucleosynthesis network calculations. Although well known for the majority of the stable isotopes, this quantity is still unknown for most of the unstable isotopes of interest. A recent collaboration between ILL, PSI, U. Sevilla and IFIC aims at producing the isotopes of interest at ILL, preparing suitable targets at PSI, and measuring their capture cross sections at facilities such as n_TOF/CERN, LiLiT and the Budapest Research Reactor (BRR). This work is focused on the description of the different beams and techniques and shows some highlights of the preliminary results of the capture measurements on 171Tm, 147Pm and 204Tl, along with the future plans for 79Se and 163Ho.

Prevalence and distribution of hepatitis C virus genotypes in Spain during the 2000-2015 period (the GEHEP 005 study)

We report the largest study on the prevalence and distribution of HCV genotypes in Spain (2000-2015), and we relate them with clinical, epidemiological and virological factors. Patients from 29 hospitals in 10 autonomous communities (Andalusia, Aragon, Castilla-Leon, Catalonia, Galicia, Canary Islands, Madrid Community, Valencian Community, Murcia Region and Basque Country) have been studied. Annual distribution of HCV genotypes and subtypes, as well as gender, age, transmission route, HIV and/or HBV coinfection, and treatment details were recorded. We included 48595 chronically HCV-infected patients with the following characteristics: median age 51 years (IQR, 44-58), 67.9% male, 19.1% HIV-coinfected, 23.5% HBV-coinfected. Parenteral transmission route was the most frequent (58.7%). Genotype distribution was 66.9% GT1 (24.9% subtype 1a and 37.9% subtype 1b), 2.8% GT2, 17.3% GT3, 11.4% GT4 and 0.1% GT5 and 0.02% GT6. LiPA was the most widely HCV genotyping test used (52.4%). HCV subtype 1a and genotypes 3 and 4 were closely associated with male gender, parenteral route of infection and HIV and HBV coinfection; in contrast, subtype 1b and genotype 2 were associated with female gender, nonparenteral route and mono-infection. Age was related to genotype distribution, and different patterns of distribution and biodiversity index were observed between different geographical areas. Finally, we describe how treatment and changes in transmission routes may have affected HCV genotype prevalence and distribution patterns. We present the most recent data on molecular epidemiology of hepatitis C virus in Spain. This study confirms that genotype distributions vary with age, sex, HIV and HBV coinfection and within geographical areas and epidemiological groups.