Pulse Shape Analysis Of Signals Research Articles

Pulse shape analysis of signals from SiPM-based CsI(Tl) detectors for low-energy protons: Saturation correction and particle identification

CsI(Tl) scintillation detectors based on a silicon photomultiplier (SiPM) were tested for low-energy proton detection. Pulse shape analysis of the SiPM signals with a transimpedance amplifier was conducted to investigate the saturation effect due to the recovery time of a pixel and to evaluate particle identification capability. To recover energy linearity, a saturation correction method based on a non-paralyzable dead time model was proposed. The setup using the SiPM with a 25 μm pixel pitch well separated protons and deuterons at energies from 3 to 12 MeV. Additionally, a readout circuit without an amplifier was tested to investigate another type of saturation due to the voltage drop effect.

Pulse shape analysis with scintillating bolometers

Rare event searches impose strict requirements to the detectors such as an excellent energy resolution, a high detection efficiency and a very low background level. The bolometric technique has already proven to be very promising in this field. Among the features on which it is possible to further act to improve the detection sensitivity, the radioactive background reduction covers a primary role. This request can be satisfied through the possibility to identify the nature of the interacting particle. However, up to now, this opportunity can be fulfilled only with a double readout (e.g. heat and scintillation light). This double readout could greatly complicate the assembly of a huge, multi-detector array. The possibility to recognize the interacting particle through the shape of the thermal pulse is therefore a very interesting opportunity.Detailed analysis of the signal time development in macro-bolometers composed by scintillating crystals showed that it is possible to distinguish between β/γ and α particle interaction (i.e. the main source of background for 0νDBD experiments based on the bolometric technique). Results of pulse shape analysis of signals from several bolometers with absorbers of different compositions (CaMoO4, ZnMoO4, ZnSe) are presented and the pulse shape discrimination capability of such detectors is discussed. An explanation of this behavior, based on the energy partition in the heat and scintillation channels, is also presented.

A novel technique of particle identification with bolometric detectors

We report in this paper the proofs that the pulse shape analysis can be used in some bolometers to identify the nature of the interacting particle. Indeed, while detailed analyses of the signal time development in purely thermal detectors have not produced so far interesting results, similar analyses on bolometers built with scintillating crystals seem to show that it is possible to distinguish between an electron or gamma-ray and an alpha particle interaction. This information can be used to eliminate background events from the recorded data in many rare process studies, especially Neutrinoless Double Beta decay search. Results of pulse shape analysis of signals from a number of bolometers with absorbers of different composition (CaMoO4, ZnMoO4, MgMoO4 and ZnSe) are presented and the pulse shape discrimination capability of such detectors is discussed.

Pulse-shape analysis of signals from monolithic silicon [formula omitted]– [formula omitted] telescopes produced by the quasi-selective epitaxy

Two monolithic E – Δ E charged particle telescopes with Δ E layers of 11 and 20 μ m thick, respectively, produced with the Quasi-Selective Epitaxy method were tested at the Heavy Ion Laboratory in Warsaw. Thorium source α -particles and 12C( 14N,X) reaction products at 80 MeV beam energy were used. During on-beam tests, detectors were placed at 20 ∘ laboratory angle with respect to the beam axis. Among the reaction products, ions of Li, Be, B, C, N, O, F were identified (using the telescope with 20 μ m Δ E layer). Pulses from both E and Δ E components of the telescope were digitalized with a digital oscilloscope, sent to a PC machine and recorded. Pulse shape analysis technique was then applied to obtain the final two dimensional spectrum. The E – Δ E two-dimensional scatter plots obtained after irradiation of the monolithic E – Δ E telescopes by α -particles from the calibration source are presented. The energy resolution of the monolithic E – Δ E telescope measured using α -particles was about 0.7 MeV for telescope with 20 μ m thick Δ E layer and 0.4 MeV for telescope with 11 μ m Δ E layer. Response of the monolythic E – Δ E telescopes for Po 212 8.78 MeV α -particles registered at different impact positions at the telescope face was measured. Cross-talk signals in the monolithic E – Δ E telescope as a function of position and the Δ E detector capacitance were simulated using the numerical solution of the telegraphic equation describing time-dependent evolution of the cross-talk potentials in the Δ E detector RC network.

Pulse shape analysis of signals from BaF 2 and CeF 3 scintillators for neutron capture experiments

The scope of this work is to study the characteristics of BaF 2 and CeF 3 signals using fast digitizers, which allow the sampling of the signal at very high frequencies and the application of the fitting method for analysis of the recorded pulses. By this procedure particle identification and the reconstruction of pile-up events can be improved, while maintaining the energy and time-of-flight resolution as compared to traditional methods. The reliability of the technique and problems connected with data acquisition are discussed with respect to accurate measurements of neutron capture cross-sections.

Wide-dynamic-range fast preamplifier for pulse shape analysis of signals from high-capacitance detectors

A new hybrid charge-sensitive preamplifier with a sensitivity of 5 mV/MeV has been specifically designed to operate in conjunction with high-capacitance silicon detectors. The shape of the leading edge of its impulse response remains fast (20 ns) and unchanged over the full output voltage range (7 V), as is required in nuclear-physics experiments in which pulse-shape analysis is used for particle identification. The circuit is miniaturized onto two sides of a ceramic substrate as small as 17/spl times/23 mm/sup 2/. A low-noise fast discharge technique is used: the return to the high-value feedback resistor (R/sub F/) comes from a noninverting low-gain (A) amplifier cascaded to the principal charge-amplifier loop. This yields a reduction of the fall time of a factor A, with no changes of C/sub F/ and R/sub F/ and no added noise. The shorter fall time reduces the pileup effects in presence of high event rates. Special care has been devoted to the matching between the high capacitance of the detector and that of the input stage of the preamplifier. To match a high capacitance, four BF862 field-effect transistors have been connected in parallel.

Pulse shape analysis of signals from a CsI(T1)/photodiode detector

Use of 1 cm 2 CsI(T1) scintillators with photodiode readout in the hard X-ray band is currently limited to above ∼ 40 keV by the lack of intrinsic gain in the photodiode and the electronic noise in the readout system. However, below this energy the photodiode itself becomes a practical X-ray detector. We report on the use of a pulse-shape analysis technique in an attempt to separate the signals from direct X-ray interactions in the photodiode and from scintillation events in the CsI(T1). We have demonstrated that separation of the two types of event is certainly possible, and the use of an appropriate spectral reconstruction algorithm enables us to normalise the signals from the two detectors. In this way we have constructed a hybrid detector capable of operating in the energy range 10 keV to 1 MeV. We discuss, using both simulations and laboratory measurements, the optimisation which can be carried out by changing the thickness of the silicon photodiode. We present details of the pulse-shape analysis system, demonstrate the identification and separation of the two types of signal, and present energy spectra for a range of energies.