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Design of electronic system for 2D hard X-ray spectrum camera on EAST 期刊论文  OAI收割
FUSION ENGINEERING AND DESIGN, 2024, 卷号: 205
作者:  Zhou, Run-Hui;  Shen, Biao;  Lin, Shi-Yao;  Cao, Hong-Rui;  Zhao, Jin-Long
  |  收藏  |  浏览/下载：4/0  |  提交时间：2024/11/22
On the Terrestrial Gamma Ray Flashes Preceding Narrow Bipolar Events 期刊论文  OAI收割
Geophysical Research Letters, 2021, 卷号: 48, 页码: e92160
作者:  HXMT
  |  收藏  |  浏览/下载：28/0  |  提交时间：2022/02/08
low frequency magnetic sferics  narrow bipolar events (NBEs)  relativistic feedback mechanism  Terrestrial Gamma ray Flashes (TGFs)  Abstract: Narrow bipolar events (NBEs) are occasionally reported to occur within a few ms after Terrestrial Gamma ray Flashes (TGFs), while the formation mechanism remains mysterious partially due to the lack of sufficient observations. Here, nine more TGFs of this scenario are reported with concurrent LF sferics and lightning location data. The gamma ray production in these TGFs preceded the occurrence of NBEs by a minimum of 60 µs up to 13.5 ms, and no other fast leader discharge was found within 20 ms before the TGF. The TGF preceded positive NBEs occurred at altitudes of 8.6-11 km in thunderstorms, likely in the high electric field (E field) region of lightning initiation. The analyses show that the NBE preceding TGFs bear harder energy spectrum with larger proportion of high energy photons than EIP related TGFs produced in association with lightning leader. Our findings support the relativistic feedback mechanism of gamma ray generation in the large scale thunderstorm E field.  
Constraining the X-Ray-Infrared Spectral Index of Second-timescale Flares from SGR 1935+2154 with Palomar Gattini-IR 期刊论文  OAI收割
The Astrophysical Journal, 2020, 卷号: 901, 页码: L7
作者:  HXMT
  |  收藏  |  浏览/下载：24/0  |  提交时间：2022/02/08
Radio transient sources  Magnetars  Soft gamma-ray repeaters  2008  992  1471  Astrophysics - High Energy Astrophysical Phenomena  Astrophysics - Instrumentation and Methods for Astrophysics  Abstract: The Galactic magnetar SGR 1935+2154 has been reported to produce the first example of a bright millisecond-duration radio burst (FRB 200428) similar to the cosmological population of fast radio bursts (FRBs). The detection of a coincident bright X-ray burst represents the first observed multiwavelength counterpart of an FRB. However, the search for similar emission at optical wavelengths has been hampered by the high inferred extinction on the line of sight. Here, we present results from the first search for second-timescale emission from the source at near-infrared (NIR) wavelengths using the Palomar Gattini-IR observing system in the J band, enabled by a novel detector readout mode that allows short exposure times of ?0.84 s with 99.9% observing efficiency. With a total observing time of ?12 hr (?47,728 images) during its 2020 outburst, we place median 3Ҡlimits on the second-timescale NIR fluence of ?18 Jy ms (13.1 AB mag). The corresponding extinction-corrected limit is ?125 Jy ms for an estimated extinction of AJ = 2.0 mag. Our observations were sensitive enough to easily detect an NIR counterpart of FRB 200428 if the NIR emission falls on the same power law as observed across its radio to X-ray spectrum. We report nondetection limits from epochs of four simultaneous X-ray bursts detected by the Insight-HXMT and NuSTAR telescopes during our observations. These limits provide the most stringent constraints to date on fluence of flares at 1014 Hz, and constrain the fluence ratio of the NIR emission to coincident X-ray bursts to RNIR ? 0.025 (fluence index ?0.35).  
Comparison of simulated backgrounds with in-orbit observations for HE, ME, and LE onboard Insight-HXMT 期刊论文  OAI收割
Astrophysics and Space Science, 2020, 卷号: 365, 页码: 158
作者:  
  |  收藏  |  浏览/下载：51/0  |  提交时间：2022/02/08
Insight-HXMT  Geant4 simulation  Background observation  Astrophysics  - Instrumentation and Methods for Astrophysics  Abstract: Insight-HXMT, the first X-ray astronomical satellite in China, aims to reveal new sources in the Galaxy and to study fundamental physics of X-ray binaries from 1 to 250 keV. It has three collimated telescopes, the High Energy X-ray telescope (HE), the Medium Energy X-ray telescope (ME), and the Low Energy X-ray telescope (LE). Before the launch, in-orbit backgrounds of these three telescopes had been estimated through Geant4 simulation, in order to investigate the instrument performance and the achievement of scientific goals. In this work, these simulated backgrounds are compared with in-orbit observations. Good agreements are shown for all three telescopes. For HE, (1) the deviation of the simulated background rate after two years of operation in space is 5 % from the observation  (2) the total background spectrum and the relative abundance of the 67 keV line show long-term increases both in simulations and observations. For ME, (1) the deviation of simulated background rate is within 15 % from the observation, and (2) there are no obvious long-term increase features in the background spectra of simulations and observations. For LE, the background level given by simulations is also consistent with observations. The consistencies of these comparisons validate that the Insight-HXMT mass model, i.e., space environment components and models adopted, physics processes selected, and detector constructions built, is reasonable. However, the line features at 7.5 and 8.0 keV, which are obvious in the observed spectra of LE, are not evident in simulations. This might result from uncertainties in the LE constructions.  
An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242 期刊论文  OAI收割
Astronomy and Astrophysics, 2020, 卷号: 641, 页码: A101
作者:  HXMT
  |  收藏  |  浏览/下载：60/0  |  提交时间：2022/02/08
accretion  accretion disks  black hole physics  X-rays: binaries  time  Astrophysics - High Energy Astrophysical Phenomena  Abstract:
Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to dominate over coronal emission. Flip-flops remain a poorly understood phenomenon, so we aim to thoroughly investigate them in a system featuring several such transitions.
Methods: Within the multitude of observations of Swift J1658.2-4242 during its outburst in early 2018, we detected 15 flip-flops, enabling a detailed analysis of their individual properties and the differences between them. We present observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analysed their light curves, searched for periodicities, computed their PDSs, and fitted their X-ray spectra, to investigate the source behaviour during flip-flop transitions and how the interval featuring flip-flops differs from the rest of the outburst.
Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within 100 s, which is much larger than what has been seen previously. We observed radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the quasi-periodic oscillation types C and A, which have never been observed before. Changes in the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals within the outburst, separated by about two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period of 2.761 ks in the first interval and 2.61 ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be very similar, but distinct from intervals lacking flip-flops. A change of the inner temperature of the accretion disc is responsible for most of the flux difference in the flip-flops. We also highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.  
Absolute-energy-scale calibration of argo-ybj for light primaries in multi-tev region with the moon shadow observation 期刊论文  iSwitch采集
Astroparticle physics, 2017, 卷号: 90, 页码: 20-27
作者:  Bartoli, B.;  Bernardini, P.;  Bi, X. J.;  Cao, Z.;  Catalanotti, S.
收藏  |  浏览/下载：143/0  |  提交时间：2019/04/23
Absolute-energy-scale calibration of ARGO-YBJ for light primaries in multi-TeV region with the Moon shadow observation 期刊论文  OAI收割
ASTROPARTICLE PHYSICS, 2017, 卷号: 90, 页码: 20-27
作者:  ARGO-YBJ Collaboration
  |  收藏  |  浏览/下载：91/0  |  提交时间：2019/08/27
The Prediction Algorithm of the Optimal X-Ray Tube Voltage in Variable Energy Imaging 期刊论文  OAI收割
SPECTROSCOPY AND SPECTRAL ANALYSIS, 2015, 卷号: 35, 期号: 3, 页码: 820-824
作者:  Bi Yan;  Chen Ping;  Han Yan
收藏  |  浏览/下载：22/0  |  提交时间：2016/03/30
Highlights of the ARGO-YBJ Experiment at 4,300 m a.s.l. 期刊论文  OAI收割
BRAZILIAN JOURNAL OF PHYSICS, 2014, 卷号: 44, 期号: 5, 页码: 494-503
作者:  ARGO-YBJ Collaboration
收藏  |  浏览/下载：25/0  |  提交时间：2015/12/02
XPS Study of the Thickness Nanosize Effect for Ultrathin SiO2 on Si Substrate 期刊论文  OAI收割
ACTA PHYSICO-CHIMICA SINICA, 2010, 卷号: 26, 期号: 11, 页码: 3030-3034
作者:  Zhao Zhi-Juan;  Liu Fen;  Zhao Liang-Zhong
  |  收藏  |  浏览/下载：84/0  |  提交时间：2019/04/09