31 research outputs found
Measurement of the 76 Ge ( n , γ ) cross section at the n_TOF facility at CERN
The
76
Ge
(
n
,
γ
)
reaction has been measured at the n_TOF facility at CERN via the time-of-flight technique. Neutron capture cross sections on
76
Ge
are of interest to a variety of low-background experiments, such as neutrinoless double
β
decay searches, and to nuclear astrophysics. We have determined resonance capture kernels up to 52 keV neutron energy and used the new data to calculate Maxwellian-averaged neutron capture cross sections for
k
B
T
values of 5 to 100 keV.The Austrian Science Fund (FWF) J3503The UK Science and Facilities Council. ST/M006085/1The European Research Council ERC-2015-StG No. 67749
Measurement of the prompt fission γ -rays from slow neutron-induced fission of 235 U with STEFF
© 2024 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/The average energy and multiplicity of prompt γ-rays from slow neutron-induced fission of 235U have been measured using the STEFF spectrometer at the neutron time-of-flight facility n_TOF. The individual responses from 11 NaI scintillators were corrected for multiple γ-ray interactions, prompt fission neutrons and background counts before being deconvolved to estimate the emitted spectrum of prompt fission γ-rays. The results give an average γ-ray energy E¯γ of 1.71(5) MeV and multiplicity ν¯γ of 2.66(18) considering γ-rays emitted within the energy range 0.8–6.8 MeV. The n_TOF data has a slightly larger E¯γ and smaller ν¯γ than other recent measurements, however the product of the two is in agreement within quoted uncertainties.Peer reviewe
Measurement of the cross section up to 200 keV at the n_TOF facility at CERN
The reaction is of importance for abundance during the slow neutron capture process in massive stars. We have performed a new measurement of the radiative neutron capture cross section at the Neutron Time-of-Flight facility at CERN. Resonance capture kernels were derived up to 51 keV and cross sections up to 200 keV. Maxwellian-averaged cross sections were calculated for stellar temperatures between and , with uncertainties between 4.2% and 5.7%. Our results lead to substantial decreases of 14% and 19% in abundances produced through the slow neutron capture process in selected stellar models of and , respectively, compared to using previous recommendation of the cross section
Measurement of the N(n,p)C cross section at the CERN n_TOF facility from sub-thermal energy to 800 keV
Background: The N(n,p)C reaction is of interest in neutron
capture therapy, where nitrogen-related dose is the main component due to
low-energy neutrons, and in astrophysics, where 14N acts as a neutron poison in
the s-process. Several discrepancies remain between the existing data obtained
in partial energy ranges: thermal energy, keV region and resonance region.
Purpose: Measuring the 14N(n,p)14C cross section from thermal to the resonance
region in a single measurement for the first time, including characterization
of the first resonances, and providing calculations of Maxwellian averaged
cross sections (MACS). Method: Time-of-flight technique. Experimental Area 2
(EAR-2) of the neutron time-of-flight (n_TOF) facility at CERN.
B(n,)Li and U(n,f) reactions as references. Two
detection systems running simultaneously, one on-beam and another off-beam.
Description of the resonances with the R-matrix code sammy. Results: The cross
section has been measured from sub-thermal energy to 800 keV resolving the two
first resonances (at 492.7 and 644 keV). A thermal cross-section
(1.8090.045 b) lower than the two most recent measurements by slightly
more than one standard deviation, but in line with the ENDF/B-VIII.0 and
JEFF-3.3 evaluations has been obtained. A 1/v energy dependence of the cross
section has been confirmed up to tens of keV neutron energy. The low energy
tail of the first resonance at 492.7 keV is lower than suggested by evaluated
values, while the overall resonance strength agrees with evaluations.
Conclusions: Our measurement has allowed to determine the N(n,p)
cross-section over a wide energy range for the first time. We have obtained
cross-sections with high accuracy (2.5 %) from sub-thermal energy to 800 keV
and used these data to calculate the MACS for kT = 5 to kT = 100 keV.Comment: 18 pages, 15 figures, 4 table
Ge() cross section below 70 keV measured at n_TOF CERN
Neutron capture reaction cross sections on Ge are of importance to determine Ge production during the astrophysical slow neutron capture process. We present new resonance data on Ge() 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
Measurement of the 76Ge(n,γ) cross section at the n_TOF facility at CERN
The Ge-76(n, gamma) reaction has been measured at the n_TOF facility at CERN via the time-of-flight technique. Neutron capture cross sections on Ge-76 are of interest to a variety of low-background experiments, such as neutrinoless double beta decay searches, and to nuclear astrophysics. We have determined resonance capture kernels up to 52 keV neutron energy and used the new data to calculate Maxwellian-averaged neutron capture cross sections for k(B)T values of 5 to 100 keV
Advances and new ideas for neutron-capture astrophysics experiments at CERN n_TOF
This article presents a few selected developments and future ideas related to the measurement of (n,γ) data of astrophysical interest at CERN n_TOF. The MC-aided analysis methodology for the use of low-efficiency radiation detectors in time-of-flight neutron-capture measurements is discussed, with particular emphasis on the systematic accuracy. Several recent instrumental advances are also presented, such as the development of total-energy detectors with γ-ray imaging capability for background suppression, and the development of an array of small-volume organic scintillators aimed at exploiting the high instantaneous neutron-flux of EAR2. Finally, astrophysics prospects related to the intermediate i neutron-capture process of nucleosynthesis are discussed in the context of the new NEAR activation area
Advances and new ideas for neutron-capture astrophysics experiments at CERN n_TOF
This article presents a few selected developments and future ideas related to the measurement of (n,γ) data of astrophysical interest at CERN n_TOF. The MC-aided analysis methodology for the use of low-efficiency radiation detectors in time-of-flight neutron-capture measurements is discussed, with particular emphasis on the systematic accuracy. Several recent instrumental advances are also presented, such as the development of total-energy detectors with γ-ray imaging capability for background suppression, and the development of an array of small-volume organic scintillators aimed at exploiting the high instantaneous neutron-flux of EAR2. Finally, astrophysics prospects related to the intermediate i neutron-capture process of nucleosynthesis are discussed in the context of the new NEAR activation area