Particle identification by digital charge comparison method applied to CsI(Tl) crystal coupled to photodiode

doi:10.1016/0168-9002(93)91267-Q

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Volume 336, Issue 3, 1 December 1993, Pages 587-590

https://doi.org/10.1016/0168-9002(93)91267-Q Get rights and content

Abstract

The application of the high energy resolution technique to the digital charge comparison method of particle identification with a CsI(Tl)-photodiode assembly allowed to get a good α-proton separation down to about 2 MeV α particles.

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Cited by (23)

Monte Carlo simulation of the passage of γ-rays and α-particles in CsI
2021, Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
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Indeed, as early as 1958 [22], it was recognized that both the efficiency and kinetics of scintillation in CsI(Tl) varied with the type and energy of radiation particles (electrons, protons, α-particles), a finding that was attributed to differences in excitation density created by the various particles. Soon after and in the following decades, techniques for particle discrimination with CsI(Tl) were put forward by researchers [23–28]. α/γ pulse shape discrimination and α/γ ratio have been studied and have consistently shown that a greater proportion of the scintillation light is promptly emitted for α-particles compared to γ-rays and that a higher Tl concentration is needed for α-particles than for γ-rays in order to reach maximum light yield [29–32] The saturation model of Murray and Meyer [33] (MM) is able to explain these observations, whereby Tl activator sites are saturated by the high excitation density created by α-particles but not in the case of γ-rays, which generally have a much lower stopping power.
Theoretical and computational methods for simulating the creation of ionization tracks by fast ions in solids were applied to the passage of α-particles in CsI, an inorganic scintillator commonly used for radiation detection. The methods were implemented in a Monte Carlo program to simulate the interaction of α-particles, with incident energies of up to 1 MeV, with CsI. The simulations followed the fate of individual electron-hole pairs and included the formation of Frenkel pairs and thus allowed for a detailed description of the microscopic structure of ionization and defect tracks created by incident radiation. Simulations were also performed with γ-rays of the same energy to compare and contrast the ionization tracks obtained with both types of particles. Intrinsic properties such as the mean energy per electron-hole pair, Fano factor, maximum theoretical light yield, and spatial distributions of electron-hole pairs were computed for both α-particles and γ-rays. α-Particles created cylindrical tracks that were initially aligned with the incident direction and with initial radii of a few tens of nanometers, whereas γ-rays showed significant scattering, resulting in probability distributions with lower intensities and much greater radial extents.
Front-end electronics for CsI based charged particle array for the study of reaction dynamics
2015, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Citation Excerpt :
Both these factors contribute to pulse shape discrimination. The commonly used pulse shape discrimination techniques for particle identification are zero cross timing technique [4], charge comparison technique [17] and ballistic deficit technique [18]. In our case we implemented the ballistic deficit technique which is very simple to implement.
The characteristics and performance of a new detector system based on CsI(TI) scintillators, and its front-end electronics are presented. The detector system has been developed for the detection of light charged particles to investigate fusion–fission dynamics, and will also serve as ancillary detector for an array of neutron detectors. CsI scintillators are read by photo-diodes. The main feature of the array is its compact and simple high density front-end electronics which includes custom developed low noise charge sensitive preamplifiers (with very low power consumption for operation inside vacuum), NIM differential drivers, and commercially available Mesytec amplifiers with two different time constants for particle identification using a ballistic deficit technique.
Energy calibration of CsI(Tl) scintillator in pulse-shape identification technique
2003, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
A batch of 16 CsI(Tl) scintillator crystals, supplied by the Bicron Company, has been studied with respect to precise energy calibration in pulse-shape identification technique. The light corresponding to pulse integration within the time interval 1.6– $4.5 μs$ (long gate) and 0.0– $4.5 μs$ (extra-long gate) exhibits a power law relation, L(E,Z,A)=a1(Z,A)E^a2(Z,A), for $^{1,2,3} H$ isotopes in the measured energy range 5– $150 MeV$ . For the time interval 0.0– $0.60 μs$ (short gate), a significant deviation from the power law relation is observed, for energy greater than $∼30 MeV$ . The character of the a2(p)–a2(d) and a2(p)–a2(t) correlations for protons, deuterons and tritons, reveals 3 types of crystals in the batch. These subbatches differ in the value of the extracted parameter a2 for protons, and in the value of the spread of a2 for deuterons and tritons. This may be explained by the difference in the energy dependence of the fast decay time component and/or by the difference in the light output ratio of the fast/slow components. An accuracy well inside 1.0% is achieved in the energy calibration of the CsI(Tl) crystals by using the ΔE(Si)–E(CsI(Tl))/PMT method. The batch of 16 CsI(Tl) crystals is utilized to measure the correlations of light charged particles produced in $E/A=61 MeV$ , $^{36} Ar$ -induced reactions. The preliminary correlation functions for two protons with small relative momenta are presented.
Particle identification method in the CsI(Tl) scintillator used for the CHIMERA 4π detector
2002, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Citation Excerpt :
Particle identification using the photodiode signal of CsI(Tl) detectors can be obtained in different ways: a standard pulse shape method, similar to the one used for neutron-γ discrimination, has been used in Ref. [4–6,8,11]; a two-gate method [7,9,12], with a simpler electronics or a combination of the two methods [10], have shown also rather good results.
The charged particle identification obtained by the analysis of signals coming from the CsI(Tl) detectors of the CHIMERA 4π heavy-ion detector is presented. A simple double-gate integration method, with the use of the cyclotron radiofrequency as reference time, results in low thresholds for isotopic particle identification. The dependence of the identification quality on the gate generation timing is discussed. Isotopic identification of light ions up to Beryllium is clearly seen. For the first time also the identification of Z=5 particles is observed. The identification of neutrons interacting with CsI(Tl) by (n,α) and (n,γ) reactions is also discussed.
Particle identification in CsI(Tl) using digital pulse shape analysis
2001, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
We developed particle identification (PID) in a CsI(Tl) crystal using digital pulse shape analysis. We present the details of the experiment, the data analysis, and the results. Four different methods of digital PID were applied to the same data set: (A) the rise-time inspection, (B) the sampling of the ADC waveform at the time of maximum waveform separation, (C) the charge comparison method with a rectangular integration window, and (D) the charge comparison method with a custom weight function. The performance of the methods A and B, which strongly depends on the bandwidth of the signal, is optimal when the bandwidth is reduced to about 0.5 MHz. The performance of the methods C and D can be only slightly improved by restricting the bandwidth. From among the four methods, the method A provides the poorest particle discrimination, while the method D provides the best. The algorithm D compares favorably with the analog charge comparison method, achieving very good proton/α-particle discrimination at energies as low as about 1 MeV, even though the measurements were carried out at the dynamic range of 35 MeV. Algorithms B, C, and D yield the PID index which is almost independent of particle energy, within the energy limits used in this work. Present results clearly show the power of digital electronics in achieving good particle identification for charged particles measured with large dynamic range.
Digital pulse processing: New possibilities in nuclear spectroscopy
2000, Applied Radiation and Isotopes
Digital pulse processing is a signal processing technique in which detector (preamplifier output) signals are directly digitized and processed to extract quantities of interest. This approach has several significant advantages compared to traditional analog signal shaping. First, analyses can be developed which take pulse-by-pulse differences into account, as in making ballistic deficit compensations. Second, transient induced charge signals, which deposit no net charge on an electrode, can be analyzed to give, for example, information on the position of interaction within the detector. Third, deadtimes from transient overload signals are greatly reduced, from tens of μs to hundreds of ns. Fourth, signals are easily captured, so that more complex analyses can be postponed until the source event has been deemed “interesting”. Fifth, signal capture and processing may easily be based on coincidence criteria between different detectors or different parts of the same detector. XIAs recently introduced CAMAC module, the DGF-4C, provides many of these features for four input channels, including two levels of digital processing and a FIFO for signal capture for each signal channel. The first level of digital processing is “immediate”, taking place in a gate array at the 40 MHz digitization rate, and implements pulse detection, pileup inspection, trapezoidal energy filtering, and control of an external 25.6 μs long FIFO. The second level of digital processing is provided by a digital signal processor (DSP), where more complex algorithms can be implemented. To illustrate digital pulse processing’s possibilities, we describe the application of the DGF-4C to a series of experiments. The first, for which the DGF was originally developed, involves locating gamma-ray interaction sites within large segmented Ge detectors. The goal of this work is to attain spatial resolutions of order 2 mm σ within 70 mm × 90 mm detectors. We show how pulse shape analysis allows ballistic deficit to be significantly reduced in these detectors. A second experiment involves studying exotic nuclei by observing their 1 MeV direct proton decays following implantation in a Si crossed stripe detector at 35 MeV. Whereas the implantation paralyzes analog electronics for almost 10 μs, the DGF allows the study of decay times as short as 1 μs. Initial energy and time resolution results are presented. Finally, we show how the DGF’s precise timing and coincidence capabilities lead to significant experimental simplifications in dealing with phoswich detectors, low background counting work, and trace Pb detection by coincident photon detection.

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Letter to the editorParticle identification by digital charge comparison method applied to CsI(Tl) crystal coupled to photodiode

Abstract

Nucl. Instr. and Meth. A

Nucl. Instr. and Meth. A

Nucl. Instr. and Meth. A

Nucl. Instr. and Meth. A

Nucl. Phys. A

Letter to the editor
Particle identification by digital charge comparison method applied to CsI(Tl) crystal coupled to photodiode