This note is providing a comparison study between the USD website and SOURCES4 calculations for the radiogenic neutron from (alpha,n) reaction.
Step 1: TENDL vs EMPIRE cross sections comparison TENDL 2011 and 2012 have been considered as the USD website inputs. TENDL is a nuclear data library (validated) which provides the output of the TALYS nuclear model code system. EMPIRE cross section are the input libraries of SOURCES4
Step 2: USD website vs SOURCES4 calculations: compare the radiogenic neutron spectra coming from both codes.
|Figure 1||Figure 2|
|Overall View||Zoom-in at the Empire Energy Range|
In this section, Fig1. and Fig2 show the spectra from USD website and SOURCES4 calculations for some materials in Tab2.: polyethylene, copper, stainless steel, titanium and borosilicate glass. Composition of materials taken into account are detailed in Tab1.
|Figure 1||Figure 2|
|SOURCES4 (alpha,n) contributions||USD website (alpha,n) contributions|
In order to check how the discrepancies from USD website and SOURCES4 calculations can affect experimental simulations, we have performed some quick simulation study, considering copper and borosilicate glass.
A standard shielding scheme - 2 layers of polyethilene and one of Lead in between - and the six copper layers of the vessel have been taken into account. Only the closer Cu cans of the experimental set-up (mixing chamber) has been contaminated with SOURCES4 and USD neutron spectra indipendently - bulk contamination, 1million neutrons from Uranium decay chain and 1 million from Th decay chain. Neutron rates in detectors from (alpha,n) reactions and spontaneous fission has been quoted from both studies.
Events simulated: 2000000
Nuclear recoils in WIMP window: 289848
Single scatter NRs in WIMP window: 99907
--- Kimberly TO UPDATE
Looking at Fig1. in section 3, Titanium is showing an high resonance at low energy ~1.5MeV. This is due to the cross section trend shown in Figures in section2. SoURCES4 cross section has a 3.5MeV peak that TENDL is not showing. By hand correcting the cross section value at 3.5MeV in SOURCES4 cross section libraries, the resonance in neutron sepctrum go away.