分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: The Dark Matter Particle Explorer (DAMPE) is being constructed as a scientific satellite to observe high energy cosmic rays in space. As a crucial detector of DAMPE, the BGO calorimeter consists of 1848 PMT dynode signals which bring difficulties in front-end electronics on the space-limited and power-limited satellite platform. To overcome the challenge, a low-noise, low-power and high-integration ASIC chip, named VA32HDR14.2, is taken into account. In order to evaluate the radiation tolerance of the chip in space radiation environment, both single event effect (SEE) and total ionizing dose (TID) tests were performed. The SEE test result shows that the effective linear energy transfer (LET) threshold of single event latch-up (SEL) of the chip is around 23.0 MeV-cm2/mg, which is relatively sensitive, thus protection methods must be taken in the electronics design. The TID test result shows that the TID performance of the chip is higher than 25 Krad(Si), which satisfies the design specification.
分类: 物理学 >> 地球物理学、天文学和天体物理学 提交时间: 2024-01-09 合作期刊: 《Research in Astronomy and Astrophysics》
摘要: Long-term spectroscopic monitoring campaigns on active galactic nuclei (AGNs) provide a wealth of information about its interior structure and kinematics. However, a number of the observations suffer from the contamination of second-order spectra (SOS) which will introduce some undesirable uncertainties at the red side of the spectra. In this paper, we test the effect of SOS and propose a method to correct it in the time domain spectroscopic data using the simultaneously observed comparison stars. Based on the reverberation mapping (RM) data of NGC 5548 in 2019, one of the most intensively monitored AGNs by the Lijiang 2.4 m telescope, we find that the scientific object, comparison star, and spectrophotometric standard star can jointly introduce up to ∼30% SOS for Grism 14. This irregular but smooth SOS significantly affects the flux density and profile of the emission line, while having little effect on the light curve. After applying our method to each spectrum, we find that the SOS can be corrected effectively. The deviation between corrected and intrinsic spectra is ∼2%, and the impact of SOS on time lag is very minor. This method makes it possible to obtain the Hα RM measurements from archival data provided that the spectral shape of the AGN under investigation does not have a large change.
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Experimental evidence is presented showing obvious azimuthal dependence of single event upsets (SEU) and multiple-bit upset (MBU) patterns in radiation hardened by design (RHBD) and MBU-sensitive static random access memories (SRAMs), due to the anisotropic device layouts. Depending on the test devices, a discrepancy from 24.5% to 50% in the SEU cross sections of dual interlock cell (DICE) SRAMs is shown between two perpendicular ion azimuths under the same tilt angle. Significant angular dependence of the SEU data in this kind of design is also observed, which does not fit the inverse-cosine law in the effective LET method. Ion trajectory-oriented MBU patterns are identified, which is also affected by the topological distribution of sensitive volumes. Due to that the sensitive volumes are periodically isolated by the BL/BLB contacts along the Y-axis direction, double-bit upsets along the X-axis become the predominant configuration under normal incidence. Predominant triple-bit upset and quadruple-bit upset patterns are the same under different ion azimuths (L-shaped and square-shaped configurations, respectively). Those results suggest that traditional RPP/IRPP model should be promoted to consider the azimuthal and angular dependence of single event effects in certain designs. During earth-based evaluation of SEE sensitivity, worst case beam direction, i.e., the worst case response, should be revealed to avoid underestimation of the on-orbit error rate.