Avalanche Counter Research Articles

Development of an Anti-Discharge Unit (ADU) for gaseous proportional counters at FRIB

Sporadic harmful discharges between the detector electrodes are inherent features of the operation of proportional counters in conditions of highly ionizing background, high gas gain, or high rate. Frequent energetic discharges can deteriorate the overall performance of the detector and cause permanent damage to the detector components. In addition, they can significantly reduce the counting rate capability of the device due to the prolonged recovery time of high-voltage power supplies.In this work, we describe the development of an Anti-Discharge Unit (ADU) implemented in a Parallel-Plate Avalanche Counter (PPAC) for heavy-ion tracking. The ADU is based on a High-Voltage (HV) MOSFET switch that shuts off the electric field between the detector electrodes within a few tens of nanoseconds when the output signal is above a fixed threshold, effectively preventing the development of streamer discharges. The avalanche field is restored within a few milliseconds so that the detector dead time is small, even in the case of moderately high spark rates. The ADU can operate effectively in conditions of high rates and highly ionizing backgrounds, in addition to enhancing the detection efficiency and extending the lifetime of the electrodes.

Development of a fast neutron monitoring detector for the NDPS neutron TOF facility by using Parallel Plate Avalanche Counters

A Parallel Plate Avalanche Counter (PPAC) neutron monitoring detector was developed and manufactured to monitor fast neutrons with energies greater than ∼1 MeV for use in the Nuclear Data Production System (NDPS), a neutron Time-of-Flight (TOF) facility of RAON. The detectors designed for monitoring fast neutrons comprise two sets of PPACs and a fast neutron converter. The performance of the detector was tested by using a241Am alpha source and neutron beams from a proton cyclotron. For the fast neutron converter, a thin thorium coating with a diameter of 60 mm was prepared by using the electrodeposition method. The areal density of thorium deposited on a thin aluminium layer with a thickness of 2 μm was determined by alpha spectrometry and measured to be 306 ± 7.65 μg/cm2. For the neutron beam test, neutrons were generated through the 9Be (p,n)9B reaction in a proton cyclotron facility. These generated neutrons were detected by using our PPAC neutron detector, and the experimentally measured count rate (1.74 ± 0.18 counts/s) agreed with the count rate (1.68 counts/s) calculated by PHITS v3.16 and GEANT4 v10.7 simulations. The timing resolution of the detector was estimated to be σ = 550 ps.

Parallel-plate avalanche counters for heavy-ion beam tracking: History and mysteries

Despite being an old detector concept, position-sensitive parallel-plate avalanche counters (PPACs) remain widely used today for heavy-ion position and timing measurements. In modern rare isotope beam facilities and large-acceptance fragment separators, PPACs are used to characterize beam properties (diagnostics), facilitate beam delivery (tuning), and provide event-by-event beam tracking for particle identification (PID). Most popular particle localization methods in PPAC detectors are based on strip electrodes electrically connected to resistive-chain circuits or delay lines. More exotic systems include optical readouts based on recording electroluminescence light with high-granularity photodetector arrays or high-resolution resistive anode electrodes. PPACs with conventional resistive-chain or delay-line readouts achieve typical position and time resolutions of below 1 mm (σ) and around 150 ps (σ), respectively. In addition, delay-line systems are capable of counting rates above several hundred kHz for beam areas of a few millimeters square, and around 1 MHz for larger beam sizes. Resistive-chain readouts have limited rates of a few tens of kHz. A review of the operation principles and performance of PPAC detectors is presented in this paper. We will discuss decades-long experience building and operating PPACs developed at the National Superconducting Cyclotron Laboratory, and then refined at the Facility for Rare Isotope Beams (FRIB), mostly focusing on the delay-line readout technique (DLPPAC). We will also discuss problems that arise due to electric discharges at high rates and briefly describe ongoing developments at FRIB. Published by the American Physical Society 2024

The development of segmented electrode thin-film parallel plate avalanche counter (PPAC)

In order to improve the counting rate and position resolution of the Parallel Plate Avalanche Counter (PPAC) within the Compact Spectrometer for Heavy Ion Experiment, a new strip film-structured PPAC has been developed. The developped PPAC detector consists of three layers of film electrodes. The upper and lower layers which serve as the anodes are comprised of self-developed strip film electrodes, oriented perpendicularly to each other. The middle layer utilizes double-sided aluminized Mylar film as the cathode. There is a 3 mm gap between each layer, and the detector has an effective area of 76 mm× 76 mm. Operating in a low-pressure environment with isobutane gas as the working medium, the performance of the PPAC has been measured using a 5.486 MeV α radiation source. The measurement results indicate that the overall position resolution of the PPAC attains approximately 380 μm, and the position resolution improves to 300 μm when using slit width correction. Finally, the Monte Carlo simulation has been performed to simulate the distribution of electrons generated by the detector's ionization under the same conditions on the anode readout strip. The simulation results closely matches the observed multiplicity of hit anode readout strips in measurement.

Development of a fast-response Parallel-Plate Avalanche Counter with strip-readout for heavy-ion beams

Abstract A strip-readout parallel-plate avalanche counter (SR-PPAC) has been developed with the aim of high-detection efficiency and good position resolution in high-intensity heavy-ion measurements. The performance was evaluated using 115 MeV u-1 132Xe, 300 MeV u-1 132Sn, and 300 MeV u-1 48Ca beams. A detection efficiency of greater than 99 percent for these beams is achieved even at an incident beam intensity of 0.7 million particles per second. The best position resolution achieved is 100 µm.

Overview of nuclear data production system at RAON

Nuclear Data Production System (NDPS), a fast neutron facility for nuclear science and applications, was constructed at the Rare Isotope Accelerator complex for ON-line experiments (RAON) in Korea. NDPS is designed to provide both white and quasi-monoenergetic neutrons using 98 MeV deuteron and 20 – 83 MeV proton beams with thick graphite and thin lithium targets, respectively. Neutron energy is determined by employing the Time-Of-Flight (TOF) technique, along with a pulsed deuteron (or proton) beam with a repetition rate of less than 200 kHz. Fast neutrons are produced in the target room and are guided to the TOF room through a 4 m long neutron collimator consisting of iron and 5% borated polyethylene. The neutron beam is monitored using a parallel plate avalanche counter (PPAC) and a micro-mesh gaseous (MICROMEGAS) detector installed in the TOF room, so as to measure the energy and the position of neutrons.

Development status of the detector system for IF separator at RAON

In-flight fragment separator at RAON aims to generate various rare isotopes and separate isotope beams of interest. A detector system for beam particle identification at the separator is being developed based on Bρ-TOF-ΔE method. Parallel plate avalanche counters, plastic scintillation detectors, and silicon detectors will be used to measure the position, timing and energy-loss of the isotopes produced by the separator. IF detector system is currently being installed at the focal planes of the IF separator. Details on the development status of the IF detector system will be discussed in this paper.

Development of Strip-Readout PPAC for high-intensity heavy ions

Strip-Readout Parallel Plate Avalanche Counters (SR-PPACs) have been developed in Center for Nuclear Study (CNS) aiming at high detection efficiency for high-intensity heavy ions based on Delay-line-readout PPAC. A readout circuit board was newly designed for the strip-readout method, and an analysis method using charge difference among two adjacent strips was developed. We achieved high detection efficiency above 99% for 115-MeV/nucleon -132Xe beams with a beam intensity of 700 kppp (particles per pulse). The achieved position resolution was about 240μm (FWHM).

Development of neutron detection systems at the NDPS of RAON

The Nuclear Data Production System (NDPS) at RAON has been built to produce nuclear data generated by the reactions induced by neutrons of tens of MeV. For the neutron Time-Of-Flight (TOF) measurement, neutron monitoring detectors based on a gas-filled Parallel Plate Avalanche Counter (PPAC) and a MICRO-MEsh-GASeous (MICROMEGAS) detector have been developed by the Rare Isotope Science Project (RISP) and Sungkyunkwan University (SKKU). These detectors have a neutron converter with a thin 232Th layer, which produces fission products due to fast neutrons. The PPAC achieved a 1 ns FWHM time resolution in a test with an 241Am α source and also showed good performance when tested with fast neutrons generated by a 45 MeV proton beam through the 9Be(p, n)9B reaction. Additionally, EJ-301, liquid scintillation detectors are assembled for the measurement of neutron flux with pulse shape discrimination capability. Slow charge signals as well as fast timing signals from the detectors will be processed for particle identification by a data acquisition (DAQ) system, located at a separate control room through 30 m long cables. Development of the detection system and the test results will be reported together with the on-site assembly status.

Recoil Proton Telescopes and Parallel Plate Avalanche Counters for the 235U(n,f) cross section measurement relative to H(n,n)H between 10 and 450 MeV neutron energy

With the aim of measuring the 235U(n,f) cross section at the n_TOF facility at CERN over a wide neutron energy range, a detection system consisting of two fission detectors and three detectors for neutron flux determination was realized. The neutron flux detectors are Recoil Proton Telescopes (RPTs), based on scintillators and solid state detectors, conceived to detect recoil protons from the neutron-proton elastic scattering reaction. This system, along with a fission chamber and an array of parallel plate avalanche counters for fission event detection, was installed for the measurement at the n_TOF facility in 2018, at CERN.An overview of the performances of two RPTs — especially developed for this measurement — and of theparallel plate avalanche counters are described in this article. In particular, the characterizationin terms of detection efficiency by Monte Carlo simulations and response to neutron beam, the studyof the background, dead time correction and characterization of the samples, are reported. Theresults of the present investigation show that the performances of these detectors are suitable foraccurate measurements of fission reaction cross sections in the range from 10 to 450 MeV.

Dynamical dipole excitation in the fission of a Ca40 + Sm152 composite system

The excitation of the dynamical dipole mode was explored in the formation of a heavy composite system with mass A≃ 190, by investigating its fission channel. The composite system was produced through the charge asymmetric reaction, Ca40 + Sm152, and the nearly charge symmetric one, Ca48 +Sm144, at Elab = 11 and 10.1 MeV/nucleon, respectively. High-energy γ rays and light charged particles were detected in coincidence with the two fission fragments by means of the MEDEA multidetector array coupled to two parallel plate avalanche counters. The kinetic energy spectra of the light charged particles measured at different angles were used to infer the average excitation energy, the average mass, and the average charge of the produced nuclei whereas the time of flight and the emission angle of the fragments were employed to reconstruct the fission dynamics. The study of the γ-ray spectra and angular distributions for the selected fission events, allowed us to establish (i) the excitation of the giant dipole resonance in the composite system of both reactions and (ii) the excitation of the dynamical dipole mode in the dinucleus of the charge asymmetric reaction by isolating its prompt γ radiation through the difference technique. The present results on the dynamical dipole mode were compared with the experimental findings for the evaporation channel of the Ca40 + Sm152 reaction and moreover with calculations based on a collective bremsstrahlung analysis of the reaction dynamics. Interesting hints connecting the dynamical dipole γ radiation with the superheavy element quest are given.10 MoreReceived 16 February 2022Accepted 6 June 2022DOI:https://doi.org/10.1103/PhysRevC.105.064611©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasFissionLow & intermediate energy heavy-ion reactionsNuclear reactionsResonance reactionsNuclear Physics

Measurement of the U235(n,f) prompt fission neutron spectrum from 10 keV to 10 MeV induced by neutrons of energy from 1 MeV to 20 MeV

The characterization of fission-driven nuclear systems primarily relies on calculations of neutron-induced chain reactions, and these calculations require evaluated nuclear data as input. Calculation accuracy heavily depends on input nuclear data evaluation accuracy, and thus high precision on the experimental input to the nuclear data evaluation is essential for fundamental quantities like the energy spectrum of neutrons emitted from neutron-induced fission (i.e., the prompt fission neutron spectrum, PFNS). Despite decades of measurement efforts, prior to the measurements described in this work there were only three literature data sets for the $^{235}\mathrm{U}(n,f)$ PFNS at incident neutron energies above 1.0 MeV considered reliable for inclusion in nuclear data evaluations and no reliable data sets above 3.0 MeV incident neutron energy. In this work we report on new measurements of the $^{235}\mathrm{U}(n,f)$ PFNS spanning a grid of 1.0--20.0 MeV in incident neutron energy and 0.01--10.0 MeV in outgoing (PFNS) neutron energy. These measurements were carried out at the Weapons Neutron Research facility at the Los Alamos Neutron Science Center and used a multifoil parallel-plate avalanche counter target with both a Li-glass and a liquid scintillator detector array in separate experiments to span the quoted outgoing neutron energy ranges. The PFNS results are shown in terms of the energy spectra themselves as well as the average PFNS energy ($\ensuremath{\langle}E\ensuremath{\rangle}$) and ratios of $\ensuremath{\langle}E\ensuremath{\rangle}$ at forward and backward angles. The results are compared with literature data and selected nuclear data evaluations. Generally, the data agree with the ENDF/B-VIII.0 evaluation below 5.0-MeV incident neutron energy and more closely with the JEFF-3.3 evaluation above 5.0 MeV, though no evaluations considered for comparison in this work agree with the data across all of the incident and outgoing neutron energies shown, especially in regions where the third-chance fission process becomes available. Additionally, we show a ratio of the present PFNS results for $^{235}\mathrm{U}(n,f)$ with a recent and highly correlated experiment to measure the $^{239}\mathrm{Pu}(n,f)$ PFNS at the same experimental facility and with nearly identical equipment and analysis procedures. Many observations reported in this work are the first of their kind and represent significant advancements for knowledge of the $^{235}\mathrm{U}(n,f)$ PFNS.

Изучение механизмов реакций с тяжелыми ионами и получение вторичных радиоактивных пучков с помощью фрагмент-сепаратора КОМБАС.

Experiments in that Be and Ta targets have been bombarded by heavy ions in series 12C, 15N, 18O, 22Ne and 40Ar are discussed. Ions was accelerated at energy 35-45 MeV/nucleon on the U-400M cyclotron at Flerov Laboratory of Nuclear Reactions, JINK. The targets were placed at the entrance focus of the COMB AS separator. Reaction products near zero-angle degrees were collected and then analyzed. The telescope formed from silicon detectors was placed at the exit achromatic focus of separator. One from pair of parallel plate avalanche counters (PPAC) has been placed at the dispersive focal plane and the other before the silicon detectors. Reaction products was identified on the mass number A and atomic number Z by the (ДЕ. K) telescope and by the (AE. T) method using lime of flight between PPAC. The measurements of the yields of isotopes were carried out by scanning the range of magnetic rigidities covering the velocity distributions of the studied isotopes. The results of the experiments was analyzed and compared with different theoretical models. The generation of radioactive beam of 11Li with maximum intensity and its purity was the objective of this experiment. Achieved maximum intensity is 104 nuclei at second.

OuroborosBEM: a fast multi-GPU microscopic Monte Carlo simulation for gaseous detectors and charged particle dynamics

The design of gaseous detectors for accelerator, particle and nuclear physics requires simulations relying on multi-physics aspects. In fact, these simulations deal with the dynamics of a large number of charged particles interacting in a gaseous medium immersed in the electric field generated by a more or less complex assembly of electrodes and dielectric materials. We report here on a homemade software, called ouroborosbem, able to tackle the different features involved in such simulations. After solving the electrostatic problem for which a solver based on the boundary element method (BEM) has been implemented, particles are tracked and will microscopically interact with the gas medium. Dynamical effects have been included such as the electron-ion recombination process, the charging-up of the dielectric materials and other space charge effects that might alter the detector performances. These were made possible thanks to the nVidia CUDA language specifically optimised to run on Graphical Processor Units (GPUs) to minimize the computing times. Comparisons of the results obtained for parallel plate avalanche counters and GEM detectors to literature data on swarm parameters fully validate the performances of ouroborosbem. Moreover, we were able to precisely reproduce the measured gains of single and double GEM detectors as a function of the applied voltage.

Fabrication and performance evaluation of parallel plate avalanche counters for RISP

We have fabricated and tested position-sensitive parallel plate avalanche counters (PPACs) for the Rare Isotope Science Project in Korea. These detectors have active areas of 10 cm × 10 cm with a stripped electrode structure. A delay line readout was employed to obtain the position information. Detector performance was tested with an 241Am alpha source. The detection efficiency, position, and time resolutions were studied with C3F8 gas pressures from 4 to 28 Torr and high voltages from 650 to 1100 V. Detection efficiency was greater than 99%. The position and time resolutions were measured to be 380 μm and 520 ps of full-width at half maximum (FWHM), respectively.

A Compact Spectrometer for Heavy Ion Experiments in the Fermi energy regime

A Compact Spectrometer for Heavy IoN Experiments (CSHINE) has been recently built for the studies of heavy ion reactions at intermediate energies. CSHINE consists of a Si-Si-CsI telescope array and a parallel plate avalanche counter (PPAC) array. Each telescope consists of a thin single-sided silicon strip detector and a thick double-sided silicon strip detector backed by a 3 × 3 CsI(Tl) crystal hodoscope. The thicknesses of the silicon detectors are optimized in order to identify various types of light charged particles in a wide energy range. PPAC is a large-area two-dimensional position-sensitive gas detector, which records fission fragments with the intrinsic efficiency of approximately 100% but filters out light charged particles at properly selected working conditions. In the phase-II run, four Si-Si-CsI telescopes and three PPACs have been installed and operated in the beam experiment with 25 MeV/u Kr+Pb reactions. Particle identification for isotopes from Hydrogen to Boron has been achieved with the Si-Si-CsI telescopes, while excellent timing and position resolution have been achieved with the PPACs.

Neutron response of the TLYC scintillator

The response of the recently developed Tl2LiYCl6(Ce) scintillator to neutrons was measured and the 35Cl(n,p) channel observed in the material for the first time. The scintillator was exposed to a 252Cf source mounted within a parallel-plate avalanche counter for fission-fragment coincident measurements. Proton- and t+α-like events are selected with the pulse-shape discrimination technique. Comparison of energy-deposition and time-of-flight allows the quenching of the different channels to be assessed. The 6Li(n,t)α channel is found to have its energy quenched to 37(1)% relative to γ-ray detection, while the proton energy deposition spectrum is quenched to 60(1)%.

CSHINE for studies of HBT correlation in heavy ion reactions

The compact spectrometer for heavy ion experiment (CSHINE) is under construction for the study of isospin chronology via the Hanbury Brown–Twiss (HBT) particle correlation function and the nuclear equation of state of asymmetrical nuclear matter. The CSHINE consists of silicon strip detector (SSD) telescopes and large-area parallel-plate avalanche counters, which measure the light charged particles and fission fragments, respectively. In phase I, two SSD telescopes were used to observe 30 MeV/u $$^{40}$$ Ar + $$^{197}$$ Au reactions. The results presented here demonstrate that hydrogen and helium were observed with high isotopic resolution, and the HBT correlation functions of light charged particles could be constructed from the obtained data.

Timing performances of a Time-Of-Flight detection system for the FRACAS large acceptance mass spectrometer

In this work, we report on the timing performances of the Time-Of-Flight (TOF) apparatus of the FRACAS large acceptance mass spectrometer designed to measure the fragmentation cross sections of a 12C beam in hadrontherapy. The TOF system is composed of a Parallel Plate Avalanche Counter and scintillating detectors to create so-called ΔE—TOF maps used in the fragment charge identification process. From tests with an alpha source and a 12C beam experiment, we measured a coincidence resolving time for the apparatus below 300 ps. Those results should lead in the final design to the identification of all the fragments produced by the interaction of 12C ions with thin targets for energies up to 400 MeV/nucleon.

Design and performance of micro-channel plate based particle tracking detector for astrophysical ([formula omitted], p) reactions

The micro-channel plate based particle tracking detector described here is part of the detector system used in a series of measurements of astrophysical (α, p) reactions, which will be studied at the Radioactive Ion Beam Line in Lanzhou, China. This detector will provide on a particle-by-particle basis tracking information and arrival time of radioactive beams with intensities up to 105 particles per second. The key requirements of the experiments to the detector are that the spatial resolution is below 1 mm, the time resolution is better than 1 ns and the energy loss is less than for a parallel plate avalanche counter. The current prototype is composed of two micro-channel plate detectors with a compact electrostatic field construction and a delay-line readout. Based on the results of α-particle tests, one micro-channel detector can achieve a position resolution of 552μm full width at half maximum on the x axis and 735μm on the y axis. The tracking system can achieve 705 ps time resolution and can cope with a beam intensity of up to 5 ×106 particles per second.