The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads of the cosmic lighthouse program onboard China's Space Station, which is planned for operation starting around 2020 for about 10 years. The main scientific objectives of HERD are indirect dark matter search, precise cosmic ray spectrum and composition measurements up to the knee energy, and high energy gamma-ray monitoring and survey. HERD is composed of a 3-D cubic calorimeter (CALO) surrounded by microstrip silicon trackers (STKs) from five sides except the bottom. CALO is made of about 10 4 cubes of LYSO crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction lengths, respectively. The top STK microstrips of seven X-Y layers are sandwiched with tungsten converters to make precise directional measurements of incoming electrons and gamma-rays. In the baseline design, each of the four side SKTs is made of only three layers microstrips. All STKs will also be used for measuring the charge and incoming directions of cosmic rays, as well as identifying back scattered tracks. With this design, HERD can achieve the following performance: energy resolution of 1% for electrons and gamma-rays beyond 100 GeV, 20% for protons from 100 GeV to 1 PeV; electron/proton separation power better than 10 −5 ; effective geometrical factors of >3 m 2 sr for electron and diffuse gamma-rays, >2 m 2 sr for cosmic ray nuclei. R&D is under way for reading out the LYSO signals with optical fiber coupled to image intensified CCD and the prototype of one layer of CALO.
The (anti-Proton ANnihiliation at DArmstadt) experiment will be one of the four flagship experiments at the new international accelerator complex FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. will address fundamental questions of hadron physics and quantum chromodynamics using high-intensity cooled antiproton beams with momenta between 1.5 and 15 GeV/c and a design luminosity of up to 2 × 1032 cm−2 s−1. Excellent particle identification (PID) is crucial to the success of the physics program. Hadronic PID in the barrel region of the target spectrometer will be performed by a fast and compact Cherenkov counter using the detection of internally reflected Cherenkov light (DIRC) technology. It is designed to cover the polar angle range from 22° to 140° and will provide at least 3 standard deviations (s.d.) π/K separation up to 3.5 GeV/c, matching the expected upper limit of the final state kaon momentum distribution from simulation. This documents describes the technical design and the expected performance of the Barrel DIRC detector. The design is based on the successful BaBar DIRC with several key improvements. The performance and system cost were optimized in detailed detector simulations and validated with full system prototypes using particle beams at GSI and CERN. The final design meets or exceeds the PID goal of clean π/K separation with at least 3 s.d. over the entire phase space of charged kaons in the Barrel DIRC.
Keywords: Rare-isotope beam, Fragment separator, 300 MeV/nucleon PACS numbers:More than 99% of the mass in the visible universethe material that makes up ourselves, our planet, stars -is in the atomic nucleus. Although the matter has existed for billions of years, only over the past few decades have we had the tools and the knowledge necessary to get a basic understanding of the structure and dynamic of nuclei. Nuclear physicists around the world have made tremendous strides by initiating a broad range of key questions that can be best attacked with various experimental probes at different beam energies. Moreover, through these efforts, we have gained access to the origin of elements and the nucleosynthesis processes that were and still are shaping the world we are living in.The energy region at around 300 MeV gives rise to the so-called energy window for nuclear structure studies. At this energy range, the distortion effects on the projectile wave functions are relatively small due to the weak strength of the scalar-isoscalar interaction, which further suppresses the multistep processes in the nuclear reaction mechanism. This brings advantages in studying nuclear spin and isospin excitations [1] and nucleon density distribution of very exotic nuclei characterized by short lifetimes and very different isospins from the stable ones [2,3]. Quantitive investigations in the two topics can yield precision information on the weak interaction processes and on how protons and neutrons are distributed in atomic nuclei. They play important roles not only in nuclear physics but also in astrophysics for stellar events such as supernovae explosions.Experimentally, such investigations are closely linked to the availability of separators and spectrometers to select and identify the rare isotopes of interest at relativistic energies of around 300 MeV/nucleon (about 65% of the speed of light). Among all the separators operating at energies more than300 MeV/nucleon worldwide, the Second Radioactive Ion Beam Line in Lanzhou (RIBLL2), one of the key components in the Heavy Ion Research Facility in Lanzhou (HIRFL-CSR) [4] at IMP, China, is unique to have an asymmetric double achromatic configuration.RIBLL2 was constructed in 2007 connecting the synchrotron cooler storage main ring (CSRm) and the experimental storage ring (CSRe) in the HIRFL-CSR complex. It has been utilized to deliver radioactive isotopes into the CSRe for mass measurements [5]. Yet its full potential as an individual experimental terminal has not been explored. The schematic layout of RIBLL2 and external target facility (ETF) is shown in Fig. 1(a).RIBLL2 has four independent sections, each consisting of a 25• dipole magnet and a set of quadrupole magnets before and after the dipole to fulfill first-order focusing conditions. Additional 8 hexapole and 4 octupole magnets are equipped for higher-order corrections. The whole separator is about 55 meters long, while the first half (F0-F2) and the second half (F2-F4) are about 26 and 29 meters, respectively. Shown in Fig...
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