We measured the energy spectra and spatial distributions of the neutron beam of Accurate Neutron-Nucleus Reaction Measurement Instrument (ANNRI) at the Japan Proton Accelerator Research ...Complex/Materials and Life Science Experimental Facility (J-PARC/MLF). Our research team designed and built ANNRI to measure nuclear data with high precision. The measurements of the neutron beam were performed on three types of beams provided by ANNRI in the neutron energy range from 1.5
meV to 10
keV. The energy spectra show a typical feature of para-hydrogen moderator, and the absolute intensities almost agree with predictions based on both a simulation calculation of the Japan Spallation Neutron Source (JSNS) and a neutron transmission calculation of the beamline. The available neutron intensities at 21.5
m are 7.5×10
5, 1.6×10
4, and 1.1×10
5
n/cm
2/s in the energy ranges 1.5–25
meV, 0.9–1.1
eV, and 0.9–1.1
keV, respectively, under the 17.5
kW JSNS operation. The measured spatial distributions of the beams formed by three different collimators are consistent with those expected from the collimator-system design of the beamline. The beam sizes in FWHM are about 29, 14, and 11
mm for the three different beam collimators. The edges of the spatial distributions are relatively sharp, enabling us to measure the nuclear data successfully.
We studied the energy resolution of the pulsed neutron beam of the Accurate Neutron–Nucleus Reaction Measurement Instrument (ANNRI) at the Japan Proton Accelerator Research Complex/Materials and Life ...Science Experimental Facility (J-PARC/MLF). A simulation in the energy region from 0.7meV to 1MeV was performed and measurements were made at thermal (0.76−62meV) and epithermal energies (4.8−410eV). The neutron energy resolution of ANNRI determined by the time-of-flight technique depends on the time structure of the neutron pulse. We obtained the neutron energy resolution as a function of the neutron energy by the simulation in the two operation modes of the neutron source: double- and single-bunch modes. In double-bunch mode, the resolution deteriorates above about 10eV because the time structure of the neutron pulse splits into two peaks. The time structures at 13 energy points from measurements in the thermal energy region agree with those of the simulation. In the epithermal energy region, the time structures at 17 energy points were obtained from measurements and agree with those of the simulation. The FWHM values of the time structures by the simulation and measurements were found to be almost consistent. In the single-bunch mode, the energy resolution is better than about 1% between 1meV and 10keV at a neutron source operation of 17.5kW. These results confirm the energy resolution of the pulsed neutron beam produced by the ANNRI beamline.
.
Neutron capture yields of dysprosium isotopes (
161
Dy,
162
Dy,
163
Dy, and
164
Dy) were measured using the time-of-flight method with a NaI(Tl) spectrometer locate at 27.9m from the spallation ...neutron target in the ANNRI beamline at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. The resonance parameters were determined using the multilevel R-matrix Bayesian code SAMMY in the neutron energy range of 1 to 300eV. Five resonances of the
161
Dy isotope, reported by Shin
et al.
but not presented in ENDF/B-VII.1, were confirmed in this study. One resonance of the
164
Dy isotope presented in ENDF/B-VII.1 was not observed in this study. The measured average level spacings were
2
.
31
±
0
.
23
eV for
161
Dy and
6
.
91
±
0
.
69
eV for
163
Dy. The statistical distributions of the resonance parameters reasonably agreed with the Porter-Tomas distributions and multiple exit channel theory.
A single collimator version of a proposed PG-SPECT system was manufactured and experimentally tested. Combining this experimental data with Monte Carlo simulation, the viability of Ge and CdTe ...semiconductors detectors was calculated. It was determined that the best detector of the ones compared would be a CdTe detector of 2–3mm, aided by the benefit of adding a Compton-suppression anti-coincidence timing detector.
•A single collimator version of a PG-SPECT system was experimentally tested.•The rate of 478keV and 2223keV gamma-rays passing through the aperture was measured.•Monte Carlo simulation was used to evaluate various semiconductor detectors.•Of the detectors simulated, a CdTe detector of thickness 2–3mm is the best.
A new data acquisition system (DAQ system) has been developed at the Accurate Neutron-Nucleus Reaction Measurement Instrument (ANNRI) facility in the Japan Proton Accelerator Research Complex, ...Materials and Life Science Experimental Facility (J-PARC/MLF). DAQ systems for both the Ge detector system and the Li-glass detector system were tested by using a gold sample. The applicability of the time-of-flight method was checked. System performance was evaluated on the basis of digital conversion nonlinearity, energy resolution, multi-channel coincidence and dead time.
The NEAR Station is a new experimental area developed at the n_TOF Facility at CERN. The activation station of NEAR underwent a characterization of the beam following the installation of the new ...n_TOF Spallation Target. The commissioning of the neutron beam comprises a set of simulations made with the FLUKA code and experimental verification. The experimental determination of the neutron spectrum was made using activation techniques with three separate set-ups. Two set-ups were based on the Multi-foil Activation technique (MAM-1 and MAM-2), and the third set-up relied on the process of neutron moderation and activation of a single material (ANTILoPE). The three set-ups are presented. Also the present plans and future perspectives of the activation station of NEAR are discussed.
The neutron time-of-flight facility n_TOF is characterised by its high instantaneous neutron intensity, high-resolution and broad neutron energy spectra, specially conceived for neutron-induced ...reaction cross section measurements. Two Time-Of-Flight (TOF) experimental areas are available at the facility: experimental area 1 (EAR1), located at the end of the 185 m horizontal flight path from the spallation target, and experimental area 2 (EAR2), placed at 20 m from the target in the vertical direction. The neutron fluence in EAR2 is ˜ 300 times more intense than in EAR1 in the relevant time-of-flight window. EAR2 was designed to carry out challenging cross-section measurements with low mass samples (approximately 1 mg), reactions with small cross-sections or/and highly radioactive samples. The high instantaneous fluence of EAR2 results in high counting rates that challenge the existing capture systems. Therefore, the sTED detector has been designed to mitigate these effects. In 2021, a dedicated campaign was done validating the performance of the detector up to at least 300 keV neutron energy. After this campaign, the detector has been used to perform various capture cross section measurements at n_TOF EAR2.
The n_TOF facility hosts CERN’s pulsed neutron source, comprising two beam lines of different flight paths and one activation station. It is based on a proton beam delivered by the PS accelerator ...impinging on a lead spallation target. During Long Shutdown 2 (LS2) at CERN (2019-2021), a major upgrade of the spallation target was carried out in order to optimize the performances of the neutron beam. Therefore, the characteristics of n_TOF two experimental areas were investigated in detail. In this work, the focus is on the second experimental area (EAR2), located 20 m above the spallation target. Preliminary results of the neutron energy distribution and beam line energy resolution are presented, compared to previous experimental campaigns and Monte Carlo simulations with the FLUKA code. Moreover, preliminary results of the spatial beam profile measurements are shown.
The neutron capture cross section of 185Re was measured in the astrophysically important energy region. Measurements were made using a neutron beam from a 7Li(p,n)7Be neutron source with energies ...ranging from 3 to 90 keV. Two different experimental techniques, time-of-flight (TOF) and activation methods, were employed. In the TOF experiments, the total neutron capture cross section of 185Re was determined by the pulse-height weighting technique. In the activation method, the partial capture cross section leading to the ground state of 186Re was measured by detecting decay γ-rays from neutron activated samples. The present cross section values were compared with evaluated cross section data and previous measurements. The difference between the TOF and activation results was smaller than experimental uncertainties. This suggests that the production cross section of isomer states of 186Re is very small.
Several international agencies recommend the study of new routes and new facilities for producing radioisotopes with application to nuclear medicine. 177Lu is a versatile radioisotope used for ...therapy and diagnosis (theranostics) of cancer with good success in neuroendocrine tumours that is being studied to be applied to a wider range of tumours. 177Lu is produced in few nuclear reactors mainly by the neutron capture on 176Lu. However, it could be produced at high-intensity celeratorbased neutron facilities. The energy of the neutrons in accelerator-based neutron facilities is higher than in thermal reactors.Thus, experimental data on the 176Yb(n,γ) cross-section in the eV and keV region are mandatory to calculate accurately the production of 177Yb, which beta decays to 177Lu. At present, there are not experimental data available from thermal to 3 keV of the 176Yb(n,γ) cross-section. In addition, there is no data in the resolved resonance region (RRR). This contribution shows the first results of the 176Yb capture measurement performed at the n_TOF facility at CERN.
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