Neutron calibration sources in the Daya Bay experiment

Abstract

We describe the design and construction of the low rate neutron calibration sources used in the Daya Bay Reactor Anti-neutrino Experiment. Such sources are free of correlated gamma-neutron emission, which is essential in minimizing induced background in the anti-neutrino detector. The design characteristics have been validated in the Daya Bay anti-neutrino detector.

Results from the first use of low radioactivity argon in a dark matter search

“…Neutrons lose energy by scattering off the nuclei in the scintillator, mostly on hydrogen and carbon, with most of its energy being lost to the former. While measurements of the scintillator's response to nuclear recoils are awaiting future calibration campaigns with an Americium-Carbon neutron source [9], measurements made with a similar scintillator in [10,11] indicate that scintilla tion from proton recoils is quenched to about 5-10% of that from electron recoils of the same kinetic energy, while carbon recoil scintillation is quenched to about 1-5%. Monte Carlo simulations have shown that the thermalization signal follows the signal in the LAr TPC very quickly, with nearly all of the energy deposited into the scintillator within ~ 100 ns of the recoil in the TPC.…”

New measurement ofθ13via neutron capture on hydrogen at Daya Bay

“…One of the calibration sources deployed from each of the three ACUs atop an AD was an 241 Am-13 C neutron source with a detected rate of 0.7 Hz [55]. Neutrons from these sources could inelastically scatter with the nuclei in the surrounding steel (SSV, ACU enclosures, etc.)…”

Calculation of Neutron Production Rates and Spectra from Compounds of Actinides and Light Elements

“…The spectra calculated by NEDIS-2.0 and measured in [6,7] are presented in Fig.1, Fig.2, and in Fig 3. Discrepancies in spectra are expected due to slowing-down of the neutrons in encapsulated sources and in the detector. The NEDIS2.0 has been used to calculate the neutron yield and spectra from the source [8]. P(Eα) -the number of α-particles with energy more than Eα was calculated in continuous-retardation approximation, neglecting fluctuations in the α-particle energy loss due to scattering and inelastic collision in Am, in 1.1 µm gold and 13 C. Results are presented in Fig.4 and in Table 4, which are in agreement with an assay of [8].…”

“…The NEDIS2.0 has been used to calculate the neutron yield and spectra from the source [8]. P(Eα) -the number of α-particles with energy more than Eα was calculated in continuous-retardation approximation, neglecting fluctuations in the α-particle energy loss due to scattering and inelastic collision in Am, in 1.1 µm gold and 13 C. Results are presented in Fig.4 and in Table 4, which are in agreement with an assay of [8].…”

“…The neutron production code NEDIS2.0 was benchmarked using the following data: experimental measurements of thick-target yields of (α,n)-neutrons from Be, BeO, BN, C, UC, UO2, Mg, Al, Si [4]; experimental data of thick-target neutron spectra of (α,n)-reaction from B, C, O, Mg, F, Al, Si, Al2O3, SiO2 measured in energy-tunable alpha-particle accelerator [5]; experimental measurements of thick-target (α,n)-reaction yields and neutron spectra from compounds of actinides with light elements [6][7][8]. In this report we present some data of neutrons yields and spectra from (α,n)-reactions and spontaneous fission.…”