IN VIVO public monitoring in emergency exposure scenarios by means of spectrometric and non-spetrometric devices

In a nuclear or radiological accident scenario, when potentially members of the public can undergo internal contamination by anthropogenic radionuclides released in the atmosphere, effective methods that can be used directly in the field to perform a fast scan for internal contamination on a large number of individuals can play a major role to undertake appropriate countermeasures. Specific attention should be paid to the individual monitoring of children since they constitute the sensitive population group with the highest risk of developing cancer. At the ENEA Casaccia Research Center in Rome (Italy), monitoring procedures based on a portable HPGe detector and ratemeters were tested in the field. A total of 170 acquisitions of uncontaminated volunteers for the blank measurements were collected, 105 acquisitions on adult and 65 acquisitions on 10-y/o children. The detection limit calculation, in terms of activity taken up (Bq), was carried out according to the Standard ISO's 11929 and 28218, whereas the corresponding 'minimum effective dose' (mSv) was calculated based on international commission on radiological protection (ICRP) Publications 134, 137 and 141. Results and evaluations of the measurement campaign are presented and discussed in respect to the aspects reported in the current literature.

Large-scale individual monitoring of internal contamination by gamma-emitting radionuclides in nuclear accident scenarios

The results obtained in a measurement campaign concerning internal contamination by the gamma-emitting radionuclides of a large number of individuals are presented in this work. The aim is to assess the effectiveness of the spectrometric method in an emergency response following a nuclear power plant accident or a spread of radionuclides in the atmosphere due to an act of terrorism. An HPGe portable spectrometer, deployed in a collective protection apparatus, was used for both whole-body and thyroid measurements. An adult bottle mannequin absorption (BOMAB) and thyroid phantoms were used to evaluate the detector performance. The BOMAB phantom was provided by the Italian Institute of Ionizing Radiation Metrology (INMRI) for the ENEA intercomparison exercise. Thyroid phantoms were provided by the Belgian Nuclear Research Centre for the 'Child and Adult Thyroid Monitoring After Reactor Accident' European intercomparison exercise. The instrument performance was further evaluated by collecting spectral data from healthy volunteers, using acquisition times of 180 s and 100 s, respectively, for the whole-body and thyroid measurements. The detector showed good accuracy in quantifying radionuclide activities in the adult BOMAB and in the thyroids of persons of all ages. The proposed method allows us to detect in vivo activity leading to a committed effective dose E(50) and committed thyroid equivalent doses H _T greater than 2 mSv due to all gamma-emitting fission products, if the scan is performed within five days after intake. Assuming, for instance, an acute inhalation of ¹³⁷Cs and ¹³¹I, the obtained detection limit values for adults lead to a E(50) value equal to 0.08 mSv and an H _T value of 0.27 mSv. The E(50) and H _T values show that the proposed method can be successfully used when the dose assessment must be rapidly performed for a large number of individuals in the eventuality of the scenarios previously mentioned.

Large-scale individual thyroid monitoring following nuclear accidents by means of non-spectrometric devices

In order to properly respond to an emergency caused by an accident in a nuclear power plant with a spread of radionuclides in the atmosphere, we propose a field procedure to perform a large-scale individual thyroid monitoring of internal contamination due to inhalation of ¹³¹I, by means of non-spectrometric equipment, in particular dose rate meters. Specific attention is paid to the individual monitoring of children, because of the very high radiosensitivity of the child's thyroid to the carcinogenic effects of ionising radiation. The device performance was evaluated by measuring mock iodine sources provided in the Child and Adult Thyroid Monitoring After Reactor Accident (CAThyMARA) intercomparison and, just for a scintillator dose rate meter, by means of 60 s acquisitions of healthy volunteers' thyroids. All the devices showed a remarkable accuracy in quantification of equivalent ¹³¹I activity in the thyroids of persons of all ages. The selected scintillator dose rate meter showed detection limit values resulting in a maximum committed equivalent dose to thyroid H_T, assuming an acute ¹³¹I inhalation occurred five days before the measurement, equal to 10 mSv (related to five-year-old children). Considering the level of H_T values associated with the calculated detection limit activities, the proposed procedure has a significant sensitivity to be used for fast internally thyroid monitoring in nuclear or radiological emergencies, allowing daily monitoring a large amount of individuals.

Measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the reaction (3)He(↑)(e,e')X

We report the first measurement of the target-normal single-spin asymmetry in deep-inelastic scattering from the inclusive reaction 3)He(↑)(e,e')X on a polarized (3)He gas target. Assuming time-reversal invariance, this asymmetry is strictly zero in the Born approximation but can be nonzero if two-photon-exchange contributions are included. The experiment, conducted at Jefferson Lab using a 5.89 GeV electron beam, covers a range of 1.7<W<2.9  GeV, 1.0<Q(2)<4.0  GeV(2) and 0.16<x<0.65. Neutron asymmetries were extracted using the effective nucleon polarization and measured proton-to-(3)He cross-section ratios. The measured neutron asymmetries are negative with an average value of (-1.09±0.38)×10(-2) for invariant mass W>2  GeV, which is nonzero at the 2.89σ level. Our measured asymmetry agrees both in sign and magnitude with a two-photon-exchange model prediction that uses input from the Sivers transverse momentum distribution obtained from semi-inclusive deep-inelastic scattering.

Beam-target double-spin asymmetry A{LT} in charged pion production from deep inelastic scattering on a transversely polarized {3}He target at 1.4<Q{2}<2.7 GeV{2}

We report the first measurement of the double-spin asymmetry A{LT} for charged pion electroproduction in semi-inclusive deep-inelastic electron scattering on a transversely polarized {3}He target. The kinematics focused on the valence quark region, 0.16<x<0.35 with 1.4<Q{2}<2.7  GeV{2}. The corresponding neutron A{LT} asymmetries were extracted from the measured {3}He asymmetries and proton over {3}He cross section ratios using the effective polarization approximation. These new data probe the transverse momentum dependent parton distribution function g{1T}{q} and therefore provide access to quark spin-orbit correlations. Our results indicate a positive azimuthal asymmetry for π{-} production on {3}He and the neutron, while our π{+} asymmetries are consistent with zero.

Single spin asymmetries in charged pion production from semi-inclusive deep inelastic scattering on a transversely polarized 3He Target at Q2 = 1.4-2.7 GeV2

We report the first measurement of target single spin asymmetries in the semi-inclusive (3)He(e,e'π(±))X reaction on a transversely polarized target. The experiment, conducted at Jefferson Lab using a 5.9 GeV electron beam, covers a range of 0.16 < x < 0.35 with 1.4 < Q(2) < 2.7 GeV(2). The Collins and Sivers moments were extracted from the azimuthal angular dependence of the measured asymmetries. The π(±) Collins moments for (3)He are consistent with zero, except for the π(+) moment at x = 0.35, which deviates from zero by 2.3σ. While the π(-) Sivers moments are consistent with zero, the π(+) Sivers moments favor negative values. The neutron results were extracted using the nucleon effective polarization and measured cross section ratios of proton to (3)He, and are largely consistent with the predictions of phenomenological fits and quark model calculations.

Observation of the naive-T-odd Sivers effect in deep-inelastic scattering

Azimuthal single-spin asymmetries of leptoproduced pions and charged kaons were measured on a transversely polarized hydrogen target. Evidence for a naive-T-odd, transverse-momentum-dependent parton distribution function is deduced from nonvanishing Sivers effects for pi(+), pi(0), and K(+/-), as well as in the difference of the pi(+) and pi(-) cross sections.