Near threshold pulse shape discrimination techniques in scintillating CsI(Tl) crystals

Cang

Nuclear Instruments and Methods in Physics Research Section A:

et al. 2016

The LaBr 3 :Ce scintillator has been widely studied for nuclear spectroscopy because of its optimal energy resolution (<3%@ 662 keV) and time resolution (~300 ps). Despite these promising properties, the intrinsic radiation background of LaBr3:Ce is a critical issue, and pulse shape discrimination (PSD) has been shown to be an efficient potential method to suppress the alpha background from the 227 Ac. In this paper, the charge comparison method (CCM) for alpha and gamma discrimination in LaBr3:Ce is quantitatively analysed and compared with two other typical PSD methods using digital pulse processing. The algorithm parameters and discrimination efficiency are calculated for each method. Moreover, for the CCM, the correlation between the CCM feature value distribution and the total charge (energy) is studied, and a fitting equation for the correlation is inferred and experimentally verified. Using the equations, an energy-dependent threshold can be chosen to optimize the discrimination efficiency. Additionally, the experimental results show a potential application in low-activity high-energy γ measurement by suppressing the alpha background.

“…As discussed in [5], for lower-energy event discrimination with the CsI(Tl) scintillator detector, Fig. 1.…”

Section: Mean Time Methods (Mtm)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantitative analysis and efficiency study of PSD methods for a LaBr3:Ce detector

Cang

Nuclear Instruments and Methods in Physics Research Section A:

et al. 2016

Nuclear Instruments and Methods in Physics Research Section A:

“…The PSD capabilities to make α/γ identification for MeV events are displayed in Figure 4a&b for both methods, indicating excellent separation. These features can be extended to the low energy regime where photo-electron statistics are limited, via advanced software techniques [24]. This is relevant to the Dark Matter experiments.…”

Section: Pulse Shape Discrimination In Csi(tl) Crystalsmentioning

confidence: 99%

Measurement of the intrinsic radiopurity of 137Cs/235U/238U/232Th in CsI(Tl) crystal scintillators

Zhu¹,

Lin²,

Singh³

et al. 2006

The inorganic crystal scintillator CsI(Tl) has been used for low energy neutrino and Dark Matter experiments, where the intrinsic radiopurity is an issue of major importance. Low-background data were taken with a CsI(Tl) crystal array at the Kuo-Sheng Reactor Neutrino Laboratory. The pulse shape discrimination capabilities of the crystal, as well as the temporal and spatial correlations of the events, provide powerful means of measuring the intrinsic radiopurity of 137 Cs as well as the 235 U, 238 U and 232 Th series. The event selection algorithms are described, with which the decay half-lives of 218 Po, 214 Po, 220 Rn, 216 Po and 212 Po were derived. The measurements of the contamination levels, their concentration gradients with the crystal growth axis, and the uniformity among different crystal samples, are reported. The radiopurity in the 238 U and 232 Th series are comparable to those of the best reported in other crystal scintillators. Significant improvements in measurement sensitivities were achieved, similar to those from dedicated massive liquid scintillator detector. This analysis also provides in situ measurements of the detector performance parameters, such as spatial resolution, quenching factors, and data acquisition dead time.

“…Also, Cs and I nuclei have relatively large spin factors for protons (S p ) that enhance the cross section for WIMP-proton spin-dependent interactions (which depend on S 2 p ). Several studies aimed at measuring the PSD capability of CsI(Tl) crystals have been performed with neutron beams generated by neutron generators [7,13] and a 252 Cf neutron source [8]. These studies demonstrated the good PSD capability of CsI(Tl) crystals in comparison with those of NaI(Tl) crystals.…”

Section: Introductionmentioning

confidence: 99%

Neutron calibration facility with an Am-Be source for pulse shape discrimination measurement of CsI(Tl) crystals

Bhang

Choi

et al. 2014

J. Inst.

We constructed a neutron calibration facility based on a 300-mCi Am-Be source in conjunction with a search for weakly interacting massive particle candidates for dark matter. The facility is used to study the response of CsI(Tl) crystals to nuclear recoils induced by neutrons from the Am-Be source and comparing them with the response to electron recoils produced by Compton scattering of 662-keV γ-rays from a 137 Cs source. The measured results on pulse shape discrimination (PSD) between nuclear-and electron-recoil events are quantified in terms of quality factors. A comparison with our previous result from a neutron generator demonstrate the feasibility of performing calibrations of PSD measurements using neutrons from a Am-Be source.