Heavy Ion Accelerator Facility Research Articles

Development of a non-intercepting weak beam current measurement electronics for Heavy Ion Accelerator Facility in Lanzhou.

Non-destructive measurements of low-intensity charged particle beams are particularly challenging for beam diagnostics. At the Heavy Ion Accelerator Facility in Lanzhou (HIRFL), beams with weak currents below 1 µA are often provided for experiments. The detection of such low beam current is below the threshold of typical standard beam current transformers. Therefore, a low-intensity monitoring system is developed by using a sensitive capacitive pick-up (PU) and low-noise electronics. This device measures beam currents by digitally analyzing the amplitude of the PU signals using a homodyne detection scheme. During lab tests, the amplitude nonlinearity is <0.5% in the operational range of 1 nA-45 µA and the amplitude resolution is 0.94 nA. At present, four measurement systems for low beam currents are installed at HIRFL for the monitoring of standard operating conditions with low beam currents below 1 µA. After an absolute calibration with a Faraday cup, it can be used for accurate beam intensity measurement with a current resolution of about 1 nA.

Conceptual design and simulated performance of the Barrel part of gamma array for the experimental terminal at HFRS of HIAF

The Barrel of γ array, consisting of 640 CsI(Tl) crystals and covering a polar angle range from 36.4° to 135.6°, has been designed for the experimental terminals at High energy FRagment Separator of High-Intensity heavy-ion Accelerator Facility in Huizhou. Together with the existing Endcap, consisting of 1024 CsI(Tl) crystals and covering a polar angle from 15.6° to 36.4°, at the External Target Facility in Lanzhou to form a new γ array, it is expected to meet the experimental requirements for in-beam γ-ray spectroscopy technique. A Monte Carlo code based on Geant4 was implemented to study the performance of the new γ array. Taking into account the Doppler correction and the intrinsic energy resolution of the detector, the energy resolution is 5.4% (FWHM) for the Endcap and 9.8% (FWHM) for the Barrel when the energy of the emitted γ-ray is 1 MeV in the Center-of-Mass frame with the beam energy of 500 MeV/u (beam velocity β = 0.759). The full-space photopeak efficiency is greater than 40% when the energy of the emitted γ-ray is less than 5 MeV in the Center-of-Mass frame and the beam energy is less than 700 MeV/u (β = 0.821). Such performance can satisfy most of the physics requirements for in-beam γ-ray spectroscopy experiments.

Design and Implementation of Chopper Control System for HIAF

The chopper control system which is synchronized by the White Rabbit timing network is designed and implemented to meet the requirements of the chopper of ion source for the High-Intensity Heavy Ion Accelerator Facility (HIAF). The hardware system consists of timing modulation controller, waveform acquisition, parameter setting, and remote control of the chopper power supply. The software includes low-level drivers and top-level applications which are based on Experimental Physics and Industrial Control System (EPICS). The combination of hardware and software completes the interaction of timing messages with the White Rabbit network, waveform acquisition, the setting of timing modulation parameters in several running modes, and remote control of the chopper power supply, etc. The test results show that the system can achieve timing modulation with a resolution of 8 ns and waveform acquisition of embedded EPICS IOC (input/output controller) at a 125 MHz sample rate. The design, implementation, and test of the chopper control system are described in this paper.

Design and Implementation of Chopper Control System for HIAF

The chopper control system which is synchronized by the White Rabbit timing network is designed and implemented to meet the requirements of the chopper of ion source for the High-Intensity Heavy Ion Accelerator Facility (HIAF). The hardware system consists of timing modulation controller, waveform acquisition, parameter setting, and remote control of the chopper power supply. The software includes low-level drivers and top-level applications which are based on Experimental Physics and Industrial Control System (EPICS). The combination of hardware and software completes the interaction of timing messages with the White Rabbit network, waveform acquisition, the setting of timing modulation parameters in several running modes, and remote control of the chopper power supply, etc. The test results show that the system can achieve timing modulation with a resolution of 8 ns and waveform acquisition of embedded EPICS IOC (input/output controller) at a 125 MHz sample rate. The design, implementation, and test of the chopper control system are described in this paper.

Ion-optical updates and performance analysis of High energy FRagment Separator (HFRS) at HIAF

The High energy FRagment Separator (HFRS), a new generation in-flight radioactive separator, is under construction at the high-intensity Heavy Ion Accelerator Facility (HIAF) in China. To further optimize the separator performance and consider the manufacturing technology, the specifications of some magnetic elements of the HFRS separator have been modified from the original design reported earlier, and prototypes of partial magnetic elements have been fabricated and tested. In this paper, updates of magnetic parameters, test results of prototypes, and development of ion-optical calculation are presented. The high-order correction of aberrations is demonstrated. The performance of the separator is studied using fission reactions and fragmentation reactions of relativistic 238U projectiles. This work will guide the forthcoming experiments in the future HFRS separator.

The HSPC — a high speed PCIe readout card for the HFRS-TPC

A new High-Speed PCI Express (PCIe) readout Card (HSPC) has been designed to transmit and aggregate data from the Time Projection Chamber (TPC) that will be assembled on High energy FRagment Separator (HFRS) beamlines at the High Intensity heavy-ion Accelerator Facility (HIAF) currently being built in Huizhou City, China. The HSPC features a high-performance controller utilizing the Xilinx Kintex Ultrascale Series Field Programmable Gate Array (FPGA), two Quad Small Form-factor Pluggable Plus (QSFP+) connectors, and a PCIe Gen3×8 interface with theoretical bandwidth of 64 Gbps. Experimental testing shows that there are no errors on the 8-fiber optics when operating at 9.6 Gbps per link, and the bit error rate (BER) is less than 1.0 × 10-15. In addition, the total read bandwidth of PCIe Gen3×8 reaches 7085.4 MB/s. Consequently, the HSPC can meet HFRS requirements.

Study on the performance of titanium alloy-lined thin-walled vacuum chamber

HIAF-BRing, the main synchrotron accelerator of the High Intensity Heavy-Ion Accelerator Facility, requires an average pressure lower than 1 × 10 −9 Pa and the magnetic field increase rate of no less than 12 T/s to fulfill radioactive beam physics and high energy density physics experiments. To reduce the eddy current effect and the gap size of dipoles, a titanium alloy-lined thin-walled vacuum chamber with a wall thickness of 0.3 mm is proposed by IMP, which has been developed from the initial ceramic-lined vacuum chamber. By mechanical loading testing, when the internal stress of titanium alloy rings made by 3D selective laser melting (SLM) reaches 639 MPa, it is still within the elastic deformation range, in fact, the yield strength of the 3D printed titanium alloy material is 912 MPa. In order to reduce the pressure gradient inside the thin-walled vacuum chamber caused by the surface outgassing of the rings, TiZrV thin films have been deposited on the rings by planar target magnetron sputtering. Through TiZrV deposited on the rings, the pressure at the middle of the thin-walled vacuum chamber has been dropped from 1.5 × 10−9 Pa to 1.0 × 10−9 Pa. At the same time, as the magnets are continuously energized, the actual heating state of the thin-walled vacuum chamber has been also measured.

Cryogenic distribution system design for cryomodules and cavities test in HIAF project

ABSTRACT High-intensity heavy-ion accelerator facility (HIAF) is an accelerator-driven high-current heavy ion facility, currently under construction in Guangdong, China. The proton linear accelerator of HIAF linac has 96 superconducting cavities and 17 cryomodules cooled by 2 K saturated superfluid helium. Cryogenic tests should be carried out in a test cryogenic system prior to the online operation of each cavity and cryomodule. The cryogenic distribution system (CDS) is the main part of the test cryogenic system, which is used for transporting cryogenic fluid between helium refrigerator and test terminals. A specific CDS is developed due to the long cryogenic test time. Each test terminal can be independently cooled and heated up, saving quite a bit of time without impacting the others. This article provides comprehensive explanations for the process design, process analysis, and special structure design which enhance the system’s maintainability. Furthermore, particular technical designs, such as measuring system, helium guard, and elimination of thermoacoustic oscillations, are described in detail.

Design and characterization of multichannel front-end electronics for detectors at HIRFL and HIAF

A multichannel front-end readout electronics (MFEE) has been designed for readout in detectors in the heavy ion facility in Lanzhou (HIRFL) and the high-intensity heavy-ion accelerator facility (HIAF). With 40 different adjustable gains, this MFEE can meet the need for most of the experiment. One MFEE can read and process the output signals of 128 channels of a detector at the same time. MFEE is based on the AD8488 chip and uses Xilinx Kintex 7 series FPGA, combined with the periphery circuits design, to complete the detector's output charge signal readout. This paper will discuss the design and performance of the MFEE.

Design of Nupix-A2, a Monolithic Active Pixel Sensor for heavy-ion physics

The High Intensity heavy-ion Accelerator Facility (HIAF) is being constructed to generate intense beams of primary and radioactive ion for a wide range of research fields. Hence, a Monolithic Active Pixel Sensor (MAPS) named Nupix-A2 has been developed in a 130-nm High Resistivity CMOS process. The Nupix-A2 can simultaneously measure the particle hit' energy, arrival time, and position. It consists of a 128 × 128 pixel array, a digital-to-analog converter array, and a digital control module. The Nupix-A2 can measure energy deposition from 300 e- to over 50 ke- and time duration from 13 μs to 140 μs. This sensor also offers full readout mode and fast readout mode. In full-readout mode, all pixels measure arrival time and energy, suitable for real-time beam monitoring and image reconstruction. In fast-readout mode, only particle hit's positions are detected and read out. This paper presents the design of the Nupix-A2.

Formation of N–O–H bearing species in HNO3 and H2O icy samples by heavy-ion irradiation: an infrared spectroscopic study

This article investigates the radiolysis of a mixture of nitric acid with water (HNO3:H2O) at 16 K in high-vacuum (residual pressure < 10−6 mbar). A nitric acid-water ice film was exposed to 40 MeV 58Ni11+ ion beam in a heavy ion accelerator facility in France. For this astrochemically- and atmospherically-relevant ice mixture of nitric acid and water, we analyze the possible formation and destruction processes of N–O bearing species, thus providing spectroscopic data in the infrared (IR) region for theoretical, laboratory and observational future studies. The irradiation synthetized 18 species which were posteriorly examined by infrared spectroscopy: N2O, NH3, NO, NO2 and H x N y O z molecules, such as hidroxylamine (NH2OH), nitrous acid (HONO) as well as other species with bonding N–O, N–H and H–O–N converting surface-adsorbed nitrogen oxides into astrochemically active NO x . The interaction of HNO3 and H2O originates H–N–O molecular complexes, which were investigated as particular cases of the hydrogen-bonded species formed by a more electronegative atom (N or O) interacts intra or intermolecularly with a donor atom (N or O) and observed in the interstellar medium with higher quantities or great abundances. The HNO3 and H2O destruction cross sections have been determined to be 8.5 × 10−13 and 1.2 × 10−13 cm2, respectively, for the mentioned experimental conditions.

Measurement and optimization of the beam coupling impedance of a novel 3D-printed titanium alloy cage inside the thin-wall vacuum chamber.

Dipole magnet vacuum chambers are among the most critical and costly components of rapid-cycling accelerator facilities. Alternative approaches to traditional ceramic chambers have been explored for the implementation of fast-ramping dipole-magnet vacuum chambers, including thin-wall metallic beam pipe chambers strengthened with transverse ribs and ceramic rings inside thin-walled chambers. Here, we report a novel 3D-printed titanium alloy cage inside the thin-wall vacuum chamber, which is designed for high-intensity heavy ion accelerator facility (HIAF) to reduce manufacturing difficulty and cost, shorten the production cycle, and improve the quality. Comprehensive studies were undertaken to characterize the impedance of the 3D-printed titanium alloy cage inside the thin-wall vacuum chamber. The beam-coupling impedance and eddy currents of the new thin-wall vacuum chamber were studied mostly numerically. Strategies for further reducing the beam-coupling impedance were explored. In addition, impedance bench measurements using the "half wavelength" resonant method were conducted to identify the longitudinal and transverse impedances of the 3D-printed titanium alloy cage inside the thin-wall vacuum chamber prototype experimentally. The simulated and measured results for the impedance were consistent. Furthermore, a campaign for resonance-check measurements on the 3D-printed titanium alloy ring loaded inside a thin-wall vacuum chamber prototype was launched. This novel thin-wall vacuum chamber structure is now entering the fabrication stage and will soon be ready for installation in the Booster Ring (BRing).

Stochastic cooling notch filter developments for the high-precision spectrometer ring in the high intensity heavy-ion accelerator facility project.

Stochastic cooling of the high-precision spectrometer ring (SRing) at the High Intensity Heavy-Ion Accelerator Facility (HIAF) project in China, which is used mainly for experiments with radioactive fragment beams, is applied to speed up the cooling process of a stored ion beam. In this article, a new coaxial-type notch filter with an amplitude equalizer in the long branch and an optical-type notch filter with phase-stabilized optical fiber are discussed and evaluated for the SRing stochastic cooling system. Both prototypes of coaxial and optical notch filters are fabricated and tested. The minimum notch depth of coaxial and optical notch filters reaches to 26 and 40 dB, respectively. The performance of both coaxial notch filter and optical fiber notch filter is presented in this work. These developments will be used not only for the longitudinal stochastic cooling system but also have potential for the beam feedback system.

Development of Allison scanner to measure transverse emittance at low energy beam transport of rare-isotope accelerator complex for ON-line experiments

The Rare-isotope Accelerator complex for ON-line experiments is a heavy-ion accelerator facility that accelerates a stable or rare isotope beam up to 400 kW with an energy of 200 MeV/u. Various heavy-ion beams are generated from the Electron Cyclotron Resonance Ion Source, with an energy of 10 keV/u and separated according to A/Q at the first dipole magnet (DM). To measure beam transverse emittance at the Low Energy Beam Transport section, two Allison scanners are installed behind the DM for the X and Y directions. It consist of a servo motor for driving, a Faraday cup for current measurement, deflection plates, and electronic device. The measurable range of beam angle in of the Allison scanner is determined by the structure of the deflection plate and designed based on mathematical calculations. Experimental Physics and Industrial Control System (EPICS) is adopted to integrate and control a variety of devices. To control the complex measurement sequence of the Allison scanner, an EPICS sequencer module was used. Normalized emittance is calculated by python code with Pyepics module using phase space distribution data. In this paper, we present the detailed design of the Allison scanner, the configuration of the control system, and the experimental results using an Ar9+ 30 μA beam.

Design, Manufacture and Test of the Superconducting Quadrupole Triplet Magnet With Multi-Layered Direct-Wound Hexapole and Octupole Magnets

Currently, the Rare Isotope Science Project of the Institute for Basic Science has been constructing a heavy ion accelerator facility, named RAON. For rare isotope science research in Korea, the RAON includes two different types of facilities; one is the isotope separation on-line, and another is the in-flight system. In the in-flight system, several types of magnets are located: dipole, quadrupole, hexapole, and octupole magnets. Among them, a superconducting quadrupole triplet magnet (SQTM) system has been developed since 2018 and to date, all SQTM systems were manufactured and are being tested. In this paper, the design, manufacture, and commissioning test results of the SQTM systems for the RAON are presented. This magnet consists of five magnets of three different kinds: three quadrupole magnets, a hexapole magnet, and an octupole magnet. All magnets were made by low-temperature superconducting NbTi wires. For manufacturing the hexapole and octupole magnets with a multi-layer structure in a narrow space, the low-temperature superconducting wire was wound by the direct winding method.

Research on the newest GaN-Based solid-state power amplifier for CiADS project

Institute of Modern Physics (IMP), Chinese Academy of Sciences is the first domestic institute to widely apply solid-state power amplifier (SSPA) to linear accelerator project from China Accelerator Driven Sub-critical System (C-ADS) project started since 2011. Until now, SSPA design has already been considered for two large-scale scientific facilities in Guangdong Province of southeast China: China initiative Accelerator Driven System (CiADS) and High Intensity Heavy-ion Accelerator Facility (HIAF). The SSPA was developed rapidly due to the reliable technologies of LDMOS-based (laterally diffused metal oxide semiconductor) power amplifiers.With the maturation of GaN (Gallium Nitride) technology, GaN-based amplifiers have been studied in the field of accelerators since 2020. Last year, IMP made new progress with GaN SSPA, measuring power modules at three fundamental frequency points of 162.5 MHz, 325 MHz, and 650 MHz. The first 50 kW rack with GaN SSPA was measured at 650 MHz in IMP, and its modules offer huge advantages of 40% output power and 8% efficiency compared to the newest LDMOS at the same frequency, which holds a fascination for our project.Until the beginning of 2023, the prototype power modules on three frequency points were completed and tested. This paper will detail the design development of GaN technology and its technical characteristics.

ISOL module system for RAON ISOL facility

RAON (Rare Isotope Accelerator complex for ON-line experiments) heavy ion accelerator facility in Korea is preparing for producing rare isotopes using Isotope Separation On-line (ISOL) facility. Rare isotopes will be produced by a 70 MeV proton beam incident on the target system. Expecting the harsh radiation environment of the target area, the module system has been adopted. The module system in the ISOL facility consists of target ion source (TIS), rare isotope (RI) transport, and proton beam diagnostic modules. In order to handle and maintain the module system, the remote handling (RH) systems are developed and tested.

NTIMP1—A Fast Pulse Readout Chip With 1.2 V Power Supply Applied to the Diamond Detector in HIAF

A very fast pulse readout ASIC, NTIMP1, with 1.2 V power supply is presented in this work. It is going to be used as front-end electronics (FEE) for reading out the diamond detector signals in the TOF (Time of Flight) wall of RIBLL2 experiment of the High Intensity Heavy Ion Accelerator Facility (HIAF), China. So that an 8-channel fast front-edge readout chip named as NTIMP1 is proposed in this work. Each channel of NTIMP1 has a high-bandwidth preamplifier (with adjustable thresholds) dealing with differential current input, a fast hysteresis discriminator, and a LVDS (Low-Voltage Differential Signaling) module ensuring long-distance signal transmission. Fabricated with 0.13 μm standard CMOS Technology, NTIMP1 can get an input ranging from 2 fC to 2000 fC and the input impedance of the preamplifier can be adjusted externally with an off-chip resistor, so as to match with the electrode impedance of diamond detector. The bandwidth of the preamplifier is 495.5 MHz, which allows a very short signal peaking time of no more than 1 ns. The jitter of the leading edge is lower than 15 ps with 100 fC input charge suggesting that NTIMP1 is suitable for high-resolution TOF measurement as well as time-slewing correction.

A Full-Waveform Digitizer for the Readout of Plastic Scintillator Detectors at HIRFL and HIAF

Being among the world’s leading heavy-ion scientific facilities, the heavy ion research facility in Lanzhou (HIRFL) and the high-intensity heavy-ion accelerator facility (HIAF) are constructed to study nuclear physics, atomic physics, nuclide chart, and heavy-ion related applications. Plastic scintillator detectors (PSD) are highly desirable and are used in large amounts for performing the experiments at HIRFL and HIAF. The PSDs are coupled with a photomultiplier tube (PMT) or silicon photomultiplier (SiPM) for converting the photons into electric signals. In this work, we develop a 16-channel full waveform digitizer (FWD) as a standard readout unit for the PSDs at HIRFL and HIAF. The FWD is based on two DRS4 chips. The design of these chips is based on the principle of a switched capacitor array (SCA), which can sample the analog signals at the GHz scale with low power consumption. In addition, the proposed FWD is designed with a general-purpose technique to reduce the development time, production cost, and maintenance difficulties. The laboratory test results show that the proposed FWD is relatively less nonlinear, i.e., about 0.6%. Its time precision is better than 15 ps. The cascade of multiple channels successfully realizes a sampling depth of 2048 cells. The joint test results of PSD show that an excellent performance in terms of measuring the cosmic rays is achieved. This paper presents the design and performance of the proposed FWD.

Design of an SHA-Less Pipeline ADC With Op-Amp Sharing Techniques for MAPS

As the leading research platform of heavy-ion science in China, the heavy-ion physics and applications at the Heavy Ion Research Facility in Lanzhou (HIRFL) and the High-Intensity heavy-ion Accelerator Facility (HIAF) drive the development of new detector technology. A monolithic active pixel sensor (MAPS) has been designed in a 130-nm CMOS process for HIRLF and HIAF. This MAPS can measure the energy deposition and position of the particle hit. As the critical component of this MAPS, a regional 12-bit 40-Msps pipeline ADC has been designed to convert the analog signals from the pixels into digital data. Due to the strict limitation on power and area, this ADC adopts the SHA-less architecture and stepwise capacitance reduction. Also, the op-amp sharing technology is used in the 1.5-bit stages. This ADC has a power consumption of 60 mW and occupies <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$874\times 550\,\,\mu \text{m}$ </tex-math></inline-formula> . Simulation results indicate that it achieves an ENOB of 11.77 bits and a SINAD of 72.57 dB at the tt corner with an input frequency of 3.291 MHz. The figure of merits (FOM) value is 507 fJ/step.