Measurements Of Neutron-induced Reactions Research Articles

MicroMegas-based detectors for time-of-flight measurements of neutron-induced reactions

MicroMegas detectors are versatile gaseous detectors which are used for ionizing particle detection. A MicroMegas detector consists of two adjacent gas-filled volumes. One volume acts as a drift region with an electric field operating in the ionization chamber regime, the second volume is the amplification region acting as a parallel-plate avalanche counter. The use of the microbulk technique allows the production of thin, radiation resistant, and low-mass detector with a highly variable gain. Such MicroMegas detectors have been developed and used in combination with neutron time-of-flight measurements for in-beam neutron-flux monitoring, fission and light-charged particle reaction cross section measurements, and for neutron-beam imaging. An overview of MicroMegas detectors for neutron detection and neutron reaction cross section measurements and related results and developments will be presented.

Recent cross-section measurements of neutron-induced reactions of importance for background estimates in0νββsearches

We report on cross-section measurements for the reactions 76 Ge(n,2n) 75 Ge, 76 Ge(n,n ′ γ) 76 Ge, 126,127,128 Te(n,γ) 127,129,131 Te, and 136 Xe(n,n ′ γ) 136 Xe in the neutron energy range between 0.5 MeV and 15 MeV.

Measurements of neutron-induced reactions in inverse kinematics and applications to nuclear astrophysics

Neutron capture cross sections of unstable isotopes are important for neutron-induced nucleosynthesis as well as for technological applications. A combination of a radioactive beam facility, an ion storage ring and a high flux reactor would allow a direct measurement of neutron induced reactions over a wide energy range on isotopes with half lives down to minutes. The idea is to measure neutron-induced reactions on radioactive ions in inverse kinematics. This means, the radioactive ions will pass through a neutron target. In order to efficiently use the rare nuclides as well as to enhance the luminosity, the exotic nuclides can be stored in an ion storage ring. The neutron target can be the core of a research reactor, where one of the central fuel elements is replaced by the evacuated beam pipe of the storage ring. Using particle detectors and Schottky spectroscopy, most of the important neutron-induced reactions, such as (n,γ), (n,p), (n,α), (n,2n), or (n,f), could be investigated.

Measurements of neutron-induced reactions in inverse kinematics

Neutron capture cross sections of unstable isotopes are important for neutron induced nucleosynthesis as well as for technological applications. A combination of a radioactive beam facility, an ion storage ring and a high flux reactor would allow a direct measurement of neutron induced reactions over a wide energy range on isotopes with half lives down to minutes.

RAON neutron science facility design for measuring neutron-induced cross-section

A heavy-ion accelerator complex called RAON is currently under development in Korea. The neutron science facility (NSF) is a part of RAON to produce white and mono-energetic neutrons covering the 10-90 MeV energy range with high-intensity. Deuterons and protons with ≤ 53 MeV and ≤ 88 MeV, respectively, accelerated by superconducting linac are delivered to the neutron target to produce fast neutrons. Pulsed beam intense is up to more than ∼ 20 μA enough for measurements of neutron-induced reactions at the neutron time-of-flight (n-TOF) facility. Be and C target are used to produce white neutrons and Li target is used for mono-energetic neutrons. Basically, two neutron beam lines at 0 ° and 30 ° will be constructed by using neutron collimator. In NSF, the time projection counter (TPC) is employed to measure fission cross-section with ∼few % uncertainty.

Cross Section Measurements of Neutron Induced Reactions on GaAs using Monoenergetic Beams from 7.5 to 15 MeV

Cross section measurements for the neutron induced reactions on GaAs have been carried out at ten different neutron energies from 7.5 to 15 MeV, using the activation technique. The monoenergetic neutron beams were produced via the 2H(d,n)3He reaction, known for it's high neutron yield in the chosen energy regime. GaAs samples were activated along with the Au and Al monitor foils, for estimating the incident neutron flux. The induced activiy was measured using high resolution γ-ray spectroscopy. Five reaction channels viz., 69Ga(n, 2n) Ga, 69Ga(n,p)69mZn, 71Ga(n,p)71mZn, 75As(n, 2n)74As and 75As(n,p)75Ge, have been reported for the comprehensive cross section measurements. The results are compared with the existing literature data and the available evaluations. Statistical model calculations, based on the Hauser-Feshbach formalism, have been carried out using the TALYS and EMPIRE codes and are compared with the experimental values.

Background (γ,n) cross section inPb208

A series of experimental estimates of the nonresonant radiative neutron reaction cross section in $^{208}\mathrm{Pb}$ have been reported recently. To date, the results from ($\ensuremath{\gamma},n$) studies have been inconsistent with measurements of neutron-induced reactions. In an effort to resolve this discrepancy, the shape of the 41-keV resonance in the reaction $^{208}\mathrm{Pb}(\ensuremath{\gamma},n)^{207}\mathrm{Pb}$ has been studied in detail by simultaneous measurements of the photoneutron spectra at 90 and 135\ifmmode^\circ\else\textdegree\fi{}. A small asymmetry in the resonance shape implies the presence of a background cross section of ${1.3}_{\ensuremath{-}0.7}^{+2.7}$ mb. This value can be explained in terms of contributions from neighboring resonances plus a small direct-reaction component; there is no evidence for anomalous processes. The result is consistent with the most recent data from study of the reaction $^{207}\mathrm{Pb}(n,{\ensuremath{\gamma}}_{0})$.[NUCLEAR REACTIONS $^{208}\mathrm{Pb}(\ensuremath{\gamma},n)$, bremsstrahlung end points 7.9, 8.4, and 9.0 MeV; studied shape 41-keV resonance, deduced background $\ensuremath{\sigma}(\ensuremath{\gamma},n)={1.3}_{\ensuremath{-}0.7}^{+2.7}$ mb.]