Institute Of High Energy Physics Research Articles

NEMA NU-4 performance evaluation of a non-human primate animal PET

The Eplus-260 primate PET is an animal PET imaging system developed by the Institute of High Energy Physics, Chinese Academy of Sciences, which is designed to image non-human primates, especially the brain of large non-human primates. The system consists of 48 block detectors arranged in two 24-sided rings with a ring diameter of 263 mm and an axial extent of 64 mm. Each block detector is composed of a 16 × 16 cerium-doped lutetium–yttrium orthosilicate crystal array with a pixel size of 1.9 × 1.9 × 10 mm3. This article presents a performance evaluation of the PET scanner according to the National Electrical Manufacturers Association NU-4 2008 standards. All measurements were made for an energy window of 360–660 keV and a coincidence timing window of 2 ns. In terms of the FWHM, the FBP reconstructed spatial resolution results in all three directions at the radial position of 5 mm were better than or approached to 2 mm, and remained below 3.0 mm within the central 5 cm diameter of the FOV. The peak absolute sensitivity of the scanner was measured 1.80%. For a monkey-sized phantom, the scatter fraction was 34.2% and the peak noise equivalent count rate (NECR) was 26.5 kcps at 64.3 kBq/cc. The overall imaging capabilities of the scanner were also assessed using in vivo imaging study of a rhesus macaque. The performance measurements demonstrate that the Eplus-260 primate PET scanner has the potential ability to obtain good quality and high-contrast images for non-human primates, especially the brain of large non-human primates and could be considered as one technologically advanced dedicated non-human primate PET scanner available today.

Design and thermal performance of spoke cavity prototype cryomodule of the Chinese Accelerator Driven Sub-critical system Injector-I

The Chinese Accelerator Driven Sub-critical system (C-ADS) Injector-I is designed and constructed by the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences (CAS) in Beijing, China. The test cryomodule (TCM), housing two 325 MHz spoke cavities and two solenoids and operating at 2 K, has been designed, assembled and commissioned since the beginning of 2012. The C-ADS Injector-I linac with the TCM successfully accelerated the proton beam to 3.68 MeV with the peak current of 10.1 mA in pulse mode. It is the world’s first prototype of spoke cavity cryomodule with beam, and is an important step in the qualification of the cryomodule before series productions. This paper describes the detail of the design, operation and thermal performances of the prototype cryomodule. The analysis takes into account the heat loads of the main components (support posts, multilayer insulation and cavities) at various cryogenic temperature levels. The estimated heat loads of the cryomodule have been compared with the available experimental measurements, and the cryogenic deformations by simulation is verified by the experimental measurements by the wire position monitors (WPMs). The operation experiences including the cool down, alignment and heat load measurement are reported. • The 325 MHz spoke cavity prototype cryomodule has been designed, assembled and commissioned. • The thermal performance of the bottom-supported cryomodule has been proved firstly worldwide. • The cryomodule can be in a stable operation at 2 K and 31 mbar with beam. • The operation experiences including the cool down, alignment and measurement of heat loads are reported. • The linac with cryomodule had been accelerated successfully to 3.68 MeV@10.1 mA in pulse mode.

Development of dipole magnet power supply for BEPC-II energy upgrading project

In order to make BEPC-II to run at a higher energy, the Institute of High Energy Physics undertook an upgrading project. One of the important factors limiting the energy boost is the power and performance of the dipole magnet power supplies; therefore, these four magnet power supplies are developed for the BEPC-II upgrading. The power supplies adopt topologies of thyristor rectifiers to realize a high-power output. In the control unit of each power supply, a digital current closed loop is adopted, and the key components in the feedback loop are thermostatically controlled. In order to improve the performances of the power supplies, analog voltage regulators are added to the inner control loops. These four power supplies have been tested and have already been officially used in BEPC-II, and their powers have reached the requirements of the upgrading. The test results of the current stability are described and shown in this paper, which testifies that the stabilities meet the design parameters. A digital control is applied to each SCR rectifier control. The performances of the power supplies are improved by the combination of digital current control loops and the analog voltage control loops, which makes the performances of the dipole magnet power supplies meet the requirements of the upgrading project.

Research and Exploit of Resource Sharing Strategy at IHEP

At IHEP (Institute of High Energy Physics, Chinese Academy of Sciences), computing resources are contributed by different experiments including BES, JUNO, DYW, HXMT, etc. The resources were divided into different partitions to satisfy the dedicated experiment data processing requirements. IHEP had a local Torqu&Maui cluster with 50 queues serving for above 10 experiments. The separated resource partitions leaded to imbalance resource load. In a typical situation, BES resource partition was quite busy without free slot but still with lots of jobs in idle, while JUNO resources are free and wasted seriously. After moving resources from Torque&Maui to HTCondor in 2016, job scheduling efficiency has been improved a lot. In order to balance the imbalance resource load, we designed an efficient sharing strategy to improve the overall resourceutilization. We created an unified pool shared by all experiments. For each experiment, resources are divided into two parts: dedicated resource and sharing resource. The slots in dedicated resource only run jobs from its own experiment, and the slots in sharing resource are shared by jobs from all experiments. Default ratio of dedicated resource to sharing resource is 1:4. To maximize the sharing effectiveness, the ratio is dynamically adjusted between 0:5 and 4:1 based on the number of jobs submitted by each experiment. We have developed a central control system to decide how many resources can be allocated to each experiment group. This system is implemented at two sides: server side and client side. A management database is built at server side, which is storing resource, group and experiment information. Once the sharing ratio needs to be adjusted, resource group will be changed and updated into database. The resource group information is published to the server buffer in real-time. The client periodically pulls resource group information from server buffer via https protocol And resource scheduling configuration at client side is changed based on the resource group information. With this method, share ratio can be modified and deployed dynamically. Sharing strategy is implemented with HTCondor. ClassAd mechanism and accounting-group in HTCondor facilitate to utilizethe sharing strategy at IHEP computing cluster. With the sharing strategy, resource usage has been improved dramatically.

Measurements of Ion Beam Composition in the Temporary Radiobiology Facility at the Institute for High Energy Physics

A detector consisting of four p-i-n silicon pad structures of size 6 × 6 mm2 and thickness 300 μm was developed for the rapid monitoring of carbon ion beam quality at the Temporary Radiobiology Facility at the Institute for High Energy Physics (TRBF IHEP) by measuring event-by-event energy release on passage of charged particles (ions) through it. This articles describes the detector design and the method used for identifying contaminants in the beam of carbon nuclei. The charge composition of the ion beam of the TRBF IHEP calculated using the amplitude spectra of signals from the p-i-n structures is presented.

A Feasibility Study on workload integration between HT-Condor and Slurm Clusters

There are two production clusters co-existed in the Institute of High Energy Physics (IHEP). One is a High Throughput Computing (HTC) cluster with HTCondor as the workload manager, the other is a High Performance Computing (HPC) cluster with Slurm as the workload manager. The resources of the HTCondor cluster are funded by multiple experiments, and the resource utilization reached more than 90% by adopting a dynamic resource share mechanism. Nevertheless, there is a bottleneck if more resources are requested by multiple experiments at the same moment. On the other hand, parallel jobs running on the Slurm cluster reflect some specific attributes, such as high degree of parallelism, low quantity and long wall time. Such attributes make it easy to generate free resource slots which are suitable for jobs from the HTCondor cluster. As a result, if there is a mechanism to schedule jobs from the HTCon-dor cluster to the Slurm cluster transparently, it would improve the resource utilization of the Slurm cluster, and reduce job queue time for the HTCondor cluster. In this proceeding, we present three methods to migrate HTCondor jobs to the Slurm cluster, and concluded that HTCondor-C is more preferred. Furthermore, because design philosophy and application scenes are di↵erent between HTCondor and Slurm, some issues and possible solutions related with job scheduling are presented.

Observation of the Independence of the p/π Ratio from the Nuclear Size for Hadrons Knocked out with Large Transverse Momenta from a Nuclear Target by 50-GeV Protons

The yields of cumulative protons and π± mesons emitted at a laboratory angle of 40° from carbon and heavier nuclear targets irradiated by a proton beam from the U70 accelerator (Institute for High Energy Physics, Protvino) have been studied in the SPIN experiment. It has been found that the effect of the target nucleus on the yield of particles with large transverse momenta is weakened.

Development and prospect of biological effects and safety of nanomaterials

Nanomaterials have lots of unique physical and chemical properties, such as quantum size effect, surface effect and macroscopic quantum tunnel effect. The biological effects of nanomaterials might be different from those of bulk materials larger than microns even if their chemical compositions are same. Therefore, the biological effects and safety evaluation results obtained from the bulk materials might not be suitable for the nanomaterials. Since 2003, governments worldwide have initiated the researches on biological effects and safety issues of nanomaterials with increasing financial support. China is one of the earliest countries in the world to carry out researches on biological effects and safety issues of nanomaterials. And some research fields have entered the forefront of the world. The CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety established jointly by National Center for Nanoscience and Technology (NCNST) and Institute of High Energy Physics of Chinese Academy of Sciences (IHEP of CAS) was the first professional laboratory focusing on the biological effects and safety of nanomaterials in China. Scientists in this laboratory have done many in-depth studies of the relationship between the physical-chemical properties and biological responses of nanomaterials. They found several factors which affected the biological effects of carbon nanotubes significantly, such as nanoparticle-Crona, metal impurities, surface, size, shape and so on. They have also established multiple models for hazard recognition and risk assessment. Nanomaterials/nanoparticles (NMs/NPs) are exposed to human beings mostly through four routes, i.e., oral intake, skin contact, inhalation, and intravenous injection. Upon entering the body, NMs/NPs are quickly distributed into specific organs and then metabolized primarily by the liver. The final excretion of NMs/NPs usually occurs in the liver and kidney in the form of urine and feces. In general, the most important issues regarding the absorption, distribution, metabolism and excretion (ADME) processes of NMs/NPs include: (1) Where do and how much NMs/NPs get in (via absorption)? (2) Where do and how much NMs/NPs go (via distribution)? (3) How much, when do, and what form of NMs/NPs remain intact (via metabolism)? (4) Where do, how much, and what form of NMs/NPs stay in the system (via excretion)? At various stages of the ADME processes, the challenges for in vivo analysis of NMs/NPs may become largely different. Important analytical methods to resolve the analytical challenges for each absorption, distribution, metabolism and excretion (ADME) process are summarized. The state-of-the art techniques with high sensitivity and high resolution suitable for safety evaluation have been developed to ensure the sustainable development of nanotechnology, such as inductively coupled plasma mass spectrometry (ICPMS), inductively coupled plasma optical emission spectrometry (ICP-OES), nuclear analysis such as neutron activation analysis (NAA), laser ablation inductively coupled plasma mass spectrometry (LAICPMS), secondary ion mass spectrometry (SIMS), synchrotron radiation X-ray fluorescence spectroscopy (SRXRF), X-ray absorption spectroscopy (XAS), X-ray fluorescence spectroscopy (XRF), scanning transmission X-ray microscopy (STXM), transmission X-ray microscopy (TXM) and so on. In this review, we summarize these research progresses in recent years.

Physics and astrophysics of strong magnetic field systems with eXTP

In this paper we present the science potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies of strongly magnetized objects. We will focus on the physics and astrophysics of strongly magnetized objects, namely magnetars, accreting X-ray pulsars, and rotation powered pulsars. We also discuss the science potential of eXTP for QED studies. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences, the eXTP mission is expected to be launched in the mid 2020s.

Superconducting 16-pole wiggler for Beijing Electron-Positron Collider II

A superconducting 16-pole 2.6T wiggler with period 170mm of The High-Energy Photon Source and the Test Facility Project (HEPS-TF) designed and fabricating in the Institute of High Energy Physics (IHEP) in China is described. This wiggler will be installed in Beijing Electron-Positron Collider II (BEPCII). The main parameters and structure of the wiggler are presented. Besides, some vertical testing results are involved.

New Capabilities of Proton Radiography for Recording Fast Gas-Dynamic Processes

For about 15 years, studies of fast gas-dynamic processes have been conducted at the Logunov Institute of Experimental Physics (VNIIEF) of the Russian Federal Nuclear Center using the proton radiography system developed jointly with the Logunov Institute of High Energy Physics on the basis of a U-70 accelerator. The main advantages of flash proton radiography over widely used flash x-ray radiography are high spatial resolution, multiframe mode, transmission capability, dynamic range of recording, etc. In recent years, effort has continued to extend the capabilities of the proton radiography system by increasing the total time and recording field and supplementing it with additional diagnostic techniques and new explosion-proof chambers. This paper presents the results of studies that illustrate these capabilities.

Observatory science with eXTP

In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.

Dense matter with eXTP

In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.

History, status and prospects of producing silicon sensors for HEP experiments at Infineon Technologies

Within this project we are developing single-sided AC-coupled silicon strip sensors and DC-coupled hexagonal pad sensors for applications in High Energy Physics (HEP) experiments. The project started with a feasibility study to re-produce the state-of-the art of silicon sensors of that time, which were based on high-resistivity n-type float-zone 6-inch silicon wafers. Later, the first silicon strip sensors on 8-inch p-type wafers were produced within this project. This influenced the decision of another project to build a silicon sensor based sampling calorimeter. This paper presents the history, current status, and prospects of this sensor development project, jointly conducted by the Institute for High Energy Physics (HEPHY) of the Austrian Academy of Sciences and Infineon Technologies AG.

Influence of cryogenic permanent magnet undulator motion error on magnetic field error and radiation intensity loss

A cryogenic permanent magnet undulator prototype designed for Chinese High Energy Photon Source Test Facility (HEPS-TF) at Institute of High Energy Physics is constructed and now commissioning. Motion precision of girders is a significant parameter to guarantee gap error so as to avoid phase error and radiation intensity loss. In order to study and minimize girder parallelism errors, RADIA and SPECTRA are used to calculate qualified motion precision. Spring Modules and single motor closed-loop feedback are designed to compensate the errors. Magnetic field is finally tuned to reach specifications. Details of the study and analysis will be presented in this paper.

Numerical Modeling of Ion-Optical Systems for Extraction of a Beam of Negative Hydrogen Ions and Its Acceleration and Matching with a Radio-Frequency Quadrupole Accelerator

A source of negative hydrogen ions is constructed at the Institute for High Energy Physics in order to raise the intensity of the U-70 accelerator complex using multiturn charge-exchange injection. The 3D ion-optical IBSimu simulation package was used to model and optimize the system for extraction of an ion beam from plasma, its acceleration to 100 keV, and matching with a radio-frequency quadrupole (RFQ) accelerator. The system of extraction of an ion beam with a current of 50 mA and electron-flow suppression was modeled. The magnetic transport channels with two solenoids and six quadrupole lenses were compared. The end goals of analysis of the matching channel were to obtain the needed Twiss parameters and to minimize the emittance growth at the RFQ input.

Quench simulation results for a 12-T twin-aperture dipole magnet

A 12-T twin-aperture subscale dipole magnet is being developed for SPPC pre-study at the Institute of High Energy Physics (IHEP). The magnet is comprised of 6 double-pancake coils which include 2 Nb3Sn coils and 4 NbTi coils. As the stored energy of the magnet is 0.452 MJ and the operation margin is only about 20% at 4.2 K, a quick and effective quench protection system is necessary during the test of this high field magnet. For the design of the quench protection system, attention was not only paid to the hotspot temperature and terminal voltage, but also the temperature gradient during the quench process due to the poor mechanical characteristics of the Nb3Sn cables. With the adiabatic analysis, numerical simulation and the finite element simulation, an optimized protection method is adopted, which contains a dump resistor and quench heaters. In this paper, the results of adiabatic analysis and quench simulation, such as current decay, hot-spot temperature and terminal voltage are presented in details.

R&D of the CEPC scintillator-tungsten ECAL

The circular electron and positron collider (CEPC) was proposed as a future Higgs factory. To meet the physics requirements, a particle flow algorithm-oriented calorimeter system with high energy resolution and precise reconstruction is considered. A sampling calorimeter with scintillator-tungsten sandwich structure is selected as one of the electromagnetic calorimeter (ECAL) options due to its good performance and relatively low cost. We present the design, the test and the optimization of the scintillator module read out by silicon photomultiplier (SiPM), including the design and the development of the electronics. To estimate the performance of the scintillator and SiPM module for particles with different energy, the beam test of a mini detector prototype without tungsten shower material was performed at the E3 beams in Institute of High Energy Physics (IHEP). The results are consistent with the expectation. These studies provide a reference and promote the development of particle flow electromagnetic calorimeter for the CEPC.

Preliminary study on protection of synchrotron radiation damage in CEPC main ring

The Circular Election–Positron Collider has been proposed by Institute of High Energy Physics (IHEP, CAS). The beam in the main ring with energy up to 120 GeV would produce intense synchrotron radiation (SR) with photon energy up to several MeV. Without shielding, this radiation would be harmful to the accelerator components. To clarify the radiation damage, analyze the source of SR, and design the shielding system to protect the accelerator. The theoretical formula has been used to estimate the spectrum and distribution of SR. Several ways of designing or shielding vacuum chamber with different geometries and various materials are put forward to protect sensitive facility components. The Monte Carlo program FLUKA has been introduced to calculate cumulative dose and heat deposition in all designing cases. The SR in CEPC main ring would be harmful to the coil used in dipole magnets. The design based on LEP with aluminum and lead would need 23 mm lead to make the coil safe. The design based on LEP with copper would need 28 mm of outer copper. And the copper chamber and lead shield design would need 16 mm of Lead. The theoretical formula has been used in source generation of Monte Carlo program to get the distribution of SR in CEPC main ring. The program was also used to simulate SR problems in the vacuum chamber with designs of different geometries and materials. Among these designs, the elliptical pipe with lead shield is preferred in CEPC.

Probing primordial gravitational waves: Ali CMB Polarization Telescope.

In this paper, we will give a general introduction to the Ali CMB Polarization Telescope (AliCPT) project, which is a Sino–US joint project led by the Institute of High Energy Physics and involves many different institutes in China. It is the first ground-based Cosmic Microwave Background (CMB) polarization experiment in China and an integral part of China's Gravitational-wave Program. The main scientific goal of the AliCPT project is to probe the primordial gravitational waves (PGWs) originating from the very early Universe. The AliCPT project includes two stages. The first stage, referred to as AliCPT-1, is to build a telescope in the Ali region of Tibet at an altitude of 5250 meters. Once completed, it will be the highest ground-based CMB observatory in the world and will open a new window for probing PGWs in the northern hemisphere. The AliCPT-1 telescope is designed to have about 7000 transition-edge sensor detectors at 95 GHz and 150 GHz. The second stage is to have a more sensitive telescope (AliCPT-2) with more than 20 000 detectors. Our simulations show that AliCPT will improve the current constraint on the tensor-to-scalar ratio r by one order of magnitude with three years' observation. Besides the PGWs, AliCPT will also enable a precise measurement of the CMB rotation angle and provide a precise test of the CPT symmetry. We show that three years' observation will improve the current limit by two orders of magnitude.