Multipurpose Spectrometer Research Articles

Characterizing Low-Energy Charged Particles in the Magnetosphere with the LEM CubeSat Spectrometer Project: Detector Concept and Hardware Characterisation

An accurate flux measurement of low-energy charged particles trapped in the magnetosphere is necessary for space weather characterization and to study the coupling between the lithosphere and magnetosphere, which allows for the investigation of the correlations between seismic events and particle precipitation from Van Allen belts. In this work, the project of a CubeSat space spectrometer, the low-energy module (LEM), is shown. The detector will be able to perform an event-based measurement of the energy, arrival direction, and composition of low-energy charged particles down to 0.1 MeV. Moreover, thanks to a CdZnTe mini-calorimeter, the LEM spectrometer also allows for photon detection in the sub-MeV range, joining the quest for the investigation of the nature of gamma-ray bursts (GRBs) and terrestrial gamma-ray flashes (TGFs). The particle identification of the LEM relies on the ΔE−E technique performed by thin silicon detectors. This multipurpose spectrometer will fit within a 10 × 10 × 10 cm3 CubeSat frame, and it will be constructed as a joint project between the University of Trento, FBK, and INFN-TIFPA. To fulfil the size and mass requirements, an innovative approach, based on active particle collimation, was designed for the LEM; this avoids the heavy/bulky passive collimators of previous space detectors. In this paper, we will present the LEM geometry, its detection concept, the results from the developed GEANT4 simulation, and some characterisations of a candidate silicon detector for the instrument payload.

Status of LAMPS at RAON

A new radioactive ion-beam accelerator facility, RAON, is under construction in Korea. Among the seven experimental systems being built, the Large Acceptance Multi-Purpose Spectrometer (LAMPS) in the high-energy experimental hall is the versatile detector system for nuclear physics. Its primary goal is to study the nuclear equation of state (EoS) and the symmetry energy of the compressed nuclear matter, which should be essential to understand the effective nuclear interactions and structure of the astrophysical objects like neutron stars. The basic LAMPS system consists of the beam diagnostic elements such as the starting counters and beam drift chambers, the time-projection chamber, the barrel and forward time-of-flight systems, the forward neutron detector array, and the superconducting solenoid magnet. In this paper the overview of the present status of each detector component for LAMPS will be given with some prospects.

J-PARC heavy ion experiment

J-PARC Heavy Ion project (J-PARC-HI) is a future fixed target experiment to study the properties of the dense matter created by the heavy-ion collisions with 1–12[Formula: see text]AGeV/[Formula: see text] at J-PARC. This project aims to search for the QCD phase boundary and its critical endpoint and to study the equation of state of the dense matter at J-PARC. For this purpose, the high-intensity beam and the precision detector with high-speed DAQ are necessary. J-PARC will be upgraded to produce the world’s highest intensity of heavy-ion beam by adding a new compact heavy-ion linac and a booster ring and utilizing the existing RCS and MR synchrotrons. We will construct the multi-purpose spectrometer with a large acceptance to measure hadrons, dileptons and photons, and their correlations and fluctuations. In these proceedings, we will report the current status of the project, the design of the detector configuration, and detector R&D.

Preliminary results from the cosmic data taking of the BESIII cylindrical GEM detectors

BESIII is a multipurpose spectrometer optimized for physics in the tau-charm energy region. Both the detector and the accelerator are undergoing an upgrade program, that will allow BESIII to run for 5 to 10 more years. A major upgrade is the replacement of the inner drift chamber with a new detector based on Cylindrical Gas Electron Multipliers to improve both the secondary vertex reconstruction and the radiation tolerance. The CGEM-IT will be composed of three coaxial layers of cylindrical triple GEMs, operating in an Ar + iC4H10 (90:10) gas mixture with field and gain optimized to minimize the spatial resolution. The new detector is readout with innovative TIGER electronics produced in 110 nm CMOS technology. The front-end is a custom designed 64 channel ASIC featuring a fully digital output and operated in trigger-less mode. It can provide analog charge and time measurements with a TDC time resolution better than 100 ps, which will allow operating in μTPC mode. With planar prototypes, we measured an unprecedented spatial resolution below 150 μm in a 1 Tesla magnetic field in a wide range of incident angles of the incoming particle. Before the installation inside BESIII, foreseen in 2021, a long standalone data taking is ongoing at the Institute of High Energy Physics in Beijing; currently, the first two cylindrical chambers are available for the test, and are used to complete the integration between the detector and the electronics and to assess the required performance. In this proceeding, a description of the CGEM-IT project, the TIGER features and performance, and the results of the analysis of first cosmic ray data taking will be presented. Focus will be given on the strip analysis, from which it is possible to measure the basic properties of the detector, and the cluster analysis, where a comparison with the results with planar prototypes will be discussed. The first preliminary results on efficiency and spatial resolution will be also presented.

Simulation and prototype testing of multi-wire drift chamber arrays for the CEE

The building of a large-scale external-target experiment, abbreviated as CEE, in the cooling storage ring at the Heavy Ion Research Facility in Lanzhou has been planned. The CEE is a multi-purpose spectrometer that will be used for various studies on heavy-ion collisions. A multi-wire drift chamber (MWDC) array is the forward tracking detector of the CEE. In this work, GEANT4 simulations were performed for the MWDC forward tracking array with a focus on the track reconstruction algorithm. Combined with the time of flight information, particle identification is achieved. The residue is about $$30\,\upmu \hbox {m}$$, while the tracking efficiency is higher than 90% with the current redundancy. In addition, a prototype of the forward tracking system using three MWDCs was assembled and tested using a high-energy proton beam. The firing efficiency of the detector and the reconstruction accuracy of the prototype were derived. The track residue for the protons at about 400 MeV/c is better than $$300\,\upmu \hbox {m}$$, meeting the requirements of the CEE. Suggestions for improving the performance of the forward tracking system are given.

Performance of prototype neutron detectors for Large Acceptance Multi-Purpose Spectrometer at RAON

Abstract The performance of the prototype modules of neutron detectors for the Large Acceptance Multi-Purpose Spectrometer (LAMPS) was investigated, using cosmic muons and neutron beams at 65 and 392 MeV, provided by the Research Center for Nuclear Physics (RCNP). The timing and position resolutions were estimated using cosmic muons as 309 ps and 4.8 cm, respectively. The energy resolution depended on the incident energy of neutrons: 1.3% at 65 MeV and 3.1% at 392 MeV. The neutron-detection efficiency also showed weak energy dependence as it decreased from (9.0 ± 1.6)% at 65 MeV to (6.3 ± 1.0)% at 392 MeV.

Development of large acceptance multi-purpose spectrometer in Korea for symmetry energy

The Rare Isotope Accelerator complex for ON-line experiments (RAON) is a new radioactive ion beam accelerator facility under construction in Korea. The large acceptance multi-purpose spectrometer (LAMPS) is one of the experimental devices for nuclear physics at RAON. It focuses on the nuclear symmetry energy at supra-saturation densities. The LAMPS Collaboration has developed and constructed various detector elements, including a time projection chamber (TPC) and a forward neutron detector array. From the positron beam test, the drift velocity of the secondary electrons in the TPC is $$5.3 \pm 0.2$$ cm/ $$\upmu $$ s with P10 gas mixture, and the position resolution for pads with dimensions of 4 $$\times $$ 15 mm $$^{2}$$ is in the range of $$\sim $$ 0.6–0.8 mm, depending on the beam position. From the neutron beam test, the energy resolution of the prototype neutron detector module is determined to be 3.4%, and the position resolution is estimated to be better than 5.28 cm. At present, the construction of the LAMPS neutron detector system is in progress.

Design of a Solenoid Magnet for the Large Acceptance Multi-Purpose Spectrometer for the Rate Isotope Science

The Large Acceptance Multi-Purpose Spectrometer (LAMPS) is one of the experimental facilities for the Rare Isotope Science Project (RISP). It will be located downstream of the Ion-flight fragment (IF) separator. The LAMPS consists of a solenoid spectrometer and a neutron detector. A time projection chamber (TPC) in the solenoid spectrometer reconstructs tracks of charged particles from nucleus-nucleus collisions under a uniform magnetic field. The size of the LAMPS solenoid magnet is about 3 × 3 × 3.5 m3, and magnetic field is ~ 0.5 T. A field uniformity (ΔB/B) of ±1% is required in the TPC region for more accurate detection of particles.

Multipurpose synchrotron spectrometer of the Kurchatov Institute: Part 3. Diffraction in Debye–Scherrer geometry

The performance of a multipurpose synchrotron spectrometer is diversified by installing additional equipment for the studies of diffraction in the Debye–Scherrer geometry. The design of X-ray optics and technical characteristics of the spectrometer are described. Diffraction patterns for polycrystals detected in both the forward and backward hemispheres are illustrated.

Prospects of nuclear physics research using rare isotope beams at RAON in Korea

Korea plans to build a new radioactive ion-beam accelerator RAON together with various experimental facilities. In particular, KOBRA(the Korea Broad Acceptance Recoil Spectrometer & Apparatus) and LAMPS(the Large-Acceptance Multi-Purpose Spectrometer) will be constructed for the nuclear physics experiments.The primary goal of KOBRA is to study the structure of exotic nuclei near drip lines and various astrophysical processes at low energies. On the other hand, LAMPS will investigate the density dependence of the nuclear symmetry energy in wide beam energy range up to 2 times normal nuclear densities. This paper provides an overview of RAON and the experimental setup for the nuclear physics program.

Simulation of the time-projection chamber with triple GEMs for the LAMPS at RAON

The time-projection chamber (TPC) with triple gas-electron multipliers (GEMs) is designed for the large-acceptance multipurpose spectrometer (LAMPS) at the new radioactive ion-beam facility RAON, a pure Korean term for the accelerator complex, in Korea. The simulation environment has been set up to test the performance of the designed chamber, and the software package for analysis has been developed. Particle identification has been demonstrated to be possible up to 2 GeV/c in momentum for particles with the charge number 1 and 2 by using the simulated heavy-ion events. The transverse-momentum resolutions are expected to be about 2% for protons and about 1.3% for pions in the relatively high-momentum region. The total reconstruction efficiencies are estimated to be about 90 and 80% for charged pions and protons, respectively.

Back-thinning process research and characteristics measurement of thin sensor

It is important to develop a thin silicon detector using a large silicon wafer to reduce multiple Coulomb scattering and the material budget. A Si-CsI detector in a large acceptance multi-purpose spectrometer (LAMPS) is considered to identify isotopes. The thickness of the first of three silicon sensors in front of the CsI(Tl) crystal is 100 μm. We aim to establish a manufacturing process for thinning using a 6-inch silicon wafer that provides the characteristics of a photodiode. In this paper, we present a back-thinning process of the photodiode, and comparisons of its electrical characteristics and signal-to-noise ratios before and after the thinning process.

Study of the design optimization of AC-coupled single-sided silicon strip sensors

The high-intensity rare-isotope accelerator, RAON, will be constructed for nuclear physics research in Korea. AC-coupled single-sided silicon strip detectors (SSSDs) are being investigated for use in the Si-CsI detector of a large acceptance multi-purpose spectrometer to measure the energies of various isotopes. To determine the optimal design, four SSSD design parameters were examined in this study, namely the ratio of p+ implant width to strip pitch (I/P), the width of the metal layer, the presence of an n+-edge field shaper (FS), and the distance between the guard-ring and sensor edge (DGS). The designed detectors were fabricated on high resistivity n-type silicon wafers of 500 μm thickness. The SSSDs had the strip pitch of 730 μm and 32 readout strips in each, and the size of the sensors was 40.0 × 25.5 mm2. In terms of the leakage current and production yield, the noise improved by up to 30%when the I/P ratio was 0.4, the metal layer was wider than the p+ implantation, and the DGS with n+-edge FS was twice the sensor thickness. The signal-to-noise ratio of the SSSD with the design parameters that provided the optimal leakage current and coupling capacitance was measured to be 29.1 using a 90Sr radioactive source and commercial electronics.

Design study for the KOBRA (KOrea Broad acceptance Recoil spectrometer and Apparatus) at RAON

The KOBRA (KOrea Broad acceptance Recoil spectrometer and Apparatus) is a multi-purpose recoil spectrometer for low-energy nuclear experiments at the RAON accelerator complex. It is divided into two stages based on the operational function: the first stage (F0–F3) is an in-flight separator or beam transport line, and the second stage (F3–F5) is a large acceptance spectrometer. For spectrometers using radioactive ion (RI) beams, high performance, such as high resolution and large acceptance, are especially required due to the limit of quality of RI beams. In this respect, a dispersion-matching technique and a movable magnet system were employed for high resolution and large acceptance, respectively. Reaction spectra at the focal plane for the dispersion matching mode were obtained and analyzed using a Monte Carlo simulation code. In addition, the geometrical angular acceptances with respect to the distance between the reaction target and the first Q-pole doublet of the second stage were calculated, and the expected maximum solid angle of the spectrometer was estimated.

System for calibrating the energy-dependent response of an elliptical Bragg-crystal spectrometer.

A multipurpose spectrometer (MSPEC) with elliptical crystals is in routine use to obtain x-ray spectra from laser produced plasmas in the energy range 1.0-9.0 keV. Knowledge of the energy-dependent response of the spectrometer is required for an accurate comparison of the intensities of x-ray lines of different energy. The energy-dependent response of the MSPEC has now been derived from the spectrometer geometry and calibration information on the response of its components, including two different types of detectors. Measurements of the spectrometer response with a laboratory x-ray source are used to test the calculated response and provide information on crystal reflectivity and uniformity.

Performance of a real-size prototype neutron detector for the LAMPS at RAON

A neutron detector array is one of the essential detector components for measuring the nuclear symmetry energy in the large-acceptance multipurpose spectrometer (LAMPS) to be built at the new radioactive ion-beam facility, RAON, in Korea. We have designed and built a real-size prototype neutron detector for the LAMPS and investigated its performance with radiation sources. The intrinsic time resolution of the prototype modules estimated by using 60Co is about 1 ns. The neutrons and the gammas from 252Cf are clearly separated in the time spectra. The kinetic energy spectrum of the fission neutrons from 252Cf has been reconstructed and compared to the empirical Watt function. The result demonstrates that the current prototypes can detect neutrons with kinetic energies larger than about 6 MeV.

Plan for nuclear symmetry energy experiments using the LAMPS system at the RIB facility RAON in Korea

A new rare isotope beam accelerator RAON and user facilities will be built in Korea. The Korea broad acceptance recoil spectrometer and apparatus (KOBRA) and the large-acceptance multipurpose spectrometer (LAMPS) will be ready from the beginning of the accelerator operation, and will be used to perform the nuclear physics experiments. We plan to use both spectrometers to investigate the density dependence of the nuclear symmetry energy in a wide range of beam energies. In particular, the high-energy setup of LAMPS, which is a combination of a solenoid and dipole spectrometers with neutron detector array, will be primarily used to study the symmetry energy of dense nuclear matter. This paper provides an overview of the RAON and the user facilities for the nuclear physics program with an emphasis on LAMPS.

Facility for Heavy Ion Collision Experiment at RAON

The Rare Isotope Science Project (RISP) was established in December 2011 in order to carry out the technical design and the establishment of the accelerator complex (RAON) for the rare isotope science in Korea. The rare isotope accelerator at RAON will provide both stable and rare isotope heavy-ion beams the energy range from a few MeV/nucleon to a few hundreds of MeV/nucleon for researches in fields of basic and applied science.Large Acceptance Multipurpose Spectrometer (LAMPS) at RAON is a heavy-ion collision experimental facility for studying nuclear symmetry energy by using rare isotope beams. Two different experimental setups of LAMPS are designed for covering entire energy range at RAON.One is for low energy (< 18.5 MeV/nucleon) heavy-ion collision experiment for day-1 experiments. This experimental setup consists of an array of ΔE-E Si-CsI detectors, a gamma array to cover backward polar angle, and a forward neutron wall.The other is for completing an event reconstruction by detecting all the particles produced in high energy heavy-ion collisions within a large acceptance angle to measure particle spectrum, yield, ratio and collective flow of pions, protons, neutrons, and intermediate fragments at the same time. The experimental setup consists of a superconducting spectrometer, a dipole spectrometer, and a forward neutron wall. A Time Projection Chamber (TPC) will be placed inside of superconducting solenoid magnet of 0.6 T for charged particle tracking. The dipole spectrometer will be located forward of the superconducting spectrometer and it will be composed of a combination of quadrupole, dipole magnets, focal plane detector, tracking stations, and Time-of-Flight (ToF) detector at the end. The neutron wall will be made of 10 layers of plastic scintillators for neutron tracking.In this presentation, the detail physics and design of LAMPS at RAON will be discussed.

Source test of the prototype neutron detector for the large-acceptance multipurpose spectrometer at RAON

A neutron detector array will be essential for the study of the nuclear symmetry energy in the large-acceptance multipurpose spectrometer (LAMPS) at the planned rare-isotope beam facility RAON in Korea. We have built the prototype neutron detector for LAMPS and examined its performance by using radiation sources. For data taking, we tested the voltage-threshold discriminator (VTD) and the constant-fraction discriminator (CFD) modules for the pulse process. The intrinsic time resolution of the prototype detector is estimated to be 723 ps for VTD and 488 ps for CFD. The fission neutrons and gammas emitted from 252Cf can be clearly separated in the time distribution. We reconstruct the energy spectrum of the spontaneous fission neutrons from 252Cf, which can be described well by using the empirical Watt spectrum.

Design of a Si-CsI detector for cluster measurements in the large-acceptance multipurpose spectrometer at RAON

We have designed a Si-CsI detector for measuring clusters from nuclear collisions in the forward region of the large-acceptance multipurpose spectrometer at RAON. The detector consists of two inclined annular rings, and covers the pseudorapidity from 1.6 to 2.1. Each ring comprises eight modules, and each module has three silicon layers and one CsI crystal bar. A realistic simulation demonstrates that the current design can identify isotopes at least up to Z = 9. The maximum measurable kinetic-energy range is distributed from 100 MeV to 1 GeV depending on the mass and Z. The Si-CsI detector will be useful for the study of the nuclear symmetry energy at RAON.