The cross section of C13(a,n)O16 has recently been directly measured in the energy range 235 - 300 keV, for the first time reaching the astrophysical energy window of the s process for the generation of heavy isotopes. By measuring deep-underground at the Gran Sasso National Laboratory (LNGS), using clean He-3 counters and applying PSD techniques for the suppression of the intrinsic background...
Neutrons and gammas produced by alpha interactions with detector materials can hide the signal searched for in low-background neutrino experiments. Despite the high purity of the materials selected, alpha particles from the U and Th chain, and in particular from the decay of $^{222}$Rn, such as $^{210}$Po, can still have a high enough rate to produced a non-negligible amount of neutrons and...
Accurate estimates of (a,n) neutron production rates, neutron energy spectra, and correlated gamma-rays are fundamental to understanding backgrounds in current and future rare-event studies. Neutrons are highly penetrating, and single scattering nuclear recoils produced by radiogenic neutrons can pose irreducible backgrounds to dark matter searches. Extensive and time consuming assay...
For many of the deep underground experiments searching for dark matter some of the most concerning neutron backgrounds come from the ($\alpha$,n) process in the cavern or detector materials. Traditionally the focus of the dark matter community has been the calculation/simulation of the background based on ($\alpha$,n) reaction evaluations and U/Th material assays. Dark matter working groups...
Next generation low-background neutrino experiments and generation-3 dark matter experiments will not only have to be located deep underground to shield cosmic induced backgrounds, but the sheer size of these next generation detectors can bring forth unprecedentedly large excavation costs. Therefore, it will be challenging to have an abundantly large passive and/or active shield around these...
Neutron production through α-induced nuclear reactions is relevant in several fields. Specifically, (α,n) reactions are interesting in nuclear astrophysics as a source of neutrons for the slow neutron capture nucleosynthesis (the s-process) [TAI16] and in the α-particle capture process (the so-called α-process) [WOO92, BLI17]. Other fields of interest include the neutron-induced background in...
The efficacy of the $s$-process in the production of heavy elements is influenced by a number of factors, including the number of neutrons available for neutron-capture reactions. Neutrons are produced by the $^{13}$C($\alpha,n$)$^{16}$O and $^{22}$Ne($\alpha,n$)$^{25}$Mg reactions, neutrons can be absorped by $^{16}$O to make $^{17}$O from which neutrons may be recycled through the...
Neutrons and gamma rays emitted from the ($a$,n) reaction are an important component of nondestructive assay techniques used in safeguards to determine enriched uranium and other actinide inventories within the nuclear fuel cycle. Uncertainties in the reaction cross section, total neutron yield, neutron spectrum, and gamma spectrum from these reactions can negatively impact the determination...
NeuCBOT, the Neutron Calculator Based On TALYS, is a tool for calculating ($\alpha$,n) neutron yields for arbitrary materials, given some activity of $\alpha$-emitting contaminants. It combines stopping power calculations from SRIM with ($\alpha$,n) cross section libraries calculated with TALYS to determine the neutron yield of materials with user-specified composition and contamination...
I will propose a new method for describing the non-resonant process in the R-matrix theory, which is associated with additional background poles which are exclusively given to the incident particles. This method was applied to the simultaneous analysis of the 6Li(p,p0)6Li, 6Li(p,a0)3He, 3He(a,a0)3He and 3He(a,p0)6Li reaction cross-sections. It was found that the present approach was necessary...
This presentation intends to review a preliminary analysis of 9Be(alpha,n)12C
integrated and angular experimental differential data at below 4MeV energy performed
at CEA Cadarache using the SAMMY code. Although not up to date, we plan to extend this
action in a near future using the CONRAD CEA code. During this work, a consistent set of
Reich-Moore resonance parameters, including possible...
Knowledge on ($\alpha$,Xn) reactions is required in several fields:
- Nuclear structure. Most of our actual experimental knowledge on
(α,Xn) reactions comes from nuclear structure experiments between the
50’s and the 70’s. Nuclear technologies, non-proliferation and
homeland security. $\alpha$-emitters present in fresh/irradiated
nuclear fuels can create a neutron source...
Sensitivity of underground experiments searching for rare events due to dark matter or neutrino interactions is often limited by the background caused by neutrons from spontaneous fission and ($\alpha,n$) reactions from naturally occurring radioisotopes. A number of computer codes are available to calculate cross-sections of ($\alpha,n$) reactions and neutron yields. We have used ...
The 3HeBF3 Giant Barrel (HeBGB) detector is a neutron counter with nearly 4pi coverage and near-constant neutron detection efficiency that was purpose built to measure (alpha,n) reaction cross sections at the Edwards Accelerator Laboratory at Ohio University. This talk will describe the design, commissioning, and first science of HeBGB. Particular emphasis will be placed on recent results...
A new evaluation of 17O system is made. The reaction channels includes:
'16O(N,N0)16O0 ' '16O(N,4HE)13C0 ' '16O(N,N1)16O1 '
'16O(N,N2)16O2 ' '16O(N,N3)16O3 ' '16O(N,N4)16O4 '
'16O(N,4HE1)13C1 ' '16O(N,4HE2)13C2 ' '16O(N,4HE3)13C3 '
'13C(4HE,4HE)13C0' '13C(4HE,N0)16O0 ' '13C(4HE,N1)16O1 '
'13C(4HE,N2)16O2 ' '13C(4HE,N3)16O3 ' '13C(4HE,N4)16O4 '...
A $^{16}$O(n,$\alpha$)$^{13}$C reaction cross section measurement was carried out at the time-of-flight facility GELINA using a Frisch-grid ionization chamber built by HZDR. Between the reaction threshold (2.36 MeV) and a neutron energy of 9 MeV, $^{16}$O(n,$\alpha_0$)$^{13}$C events could be separated well from background events.
The experimental $^{16}$O(n,$\alpha_0$)$^{13}$C data are...
The angular dependence of the differential cross-sections for the 13C(α,n0)16O reaction was measured in the energy range of 2.0-6.2 MeV using the time-of-flight method for separating neutrons corresponding to the ground state of the residual nucleus. The integrated total cross-sections were derived from the measured data and the cross-sections for the 16O(n,α0)13C reaction were determined...
Oxygen is present in many materials - water, oxides, concrete and elsewhere - and the uncertainties in its nuclear data can have a significant impact on many nuclear applications. The current status of the oxygen-16 data is a 30-50 % discrepancy among various $^{16}$O(n,$\alpha$) and $^{13}$C($\alpha$,n) cross section measurements. Reconciling these discrepancies and settling on a best value...
Improved $(\alpha,n)$ cross section measurements are needed for a range of applications such as nuclear astrophysics, neutrino physics, geophysics, nuclear energy, and weapons research. While they are sometimes focused on different energy regions, all benefit from a improved measurements over a wide energy range. The connection is further strengthened through the use of $R$-matrix analysis for...
A brief overview of the R-matrix evaluation method implemented in EDAf90 that emphasizes the relativistic model parametrization, polarization capabilities, and computational capabilities. We will review existing evaluations for (alpha,n) on material targets n, 1H, 2H, 3H, 3He, 6Li, 7Li, 11B (time permitting) and discuss recent activity on 13C in the 17O system analysis.
