Detection of liquid xenon scintillation light with a Silicon Photomultiplier

We have studied the feasibility of a silicon photomultiplier (SiPM) to detect liquid xenon (LXe) scintillation light. The SiPM was operated inside a small volume of pure LXe, at -95 degree Celsius, irradiated with an internal Am-241 alpha source. The gain of the SiPM at this temperature was estimated to be 1.8 x 10^6 with bias voltage at 52 V. Based on the geometry of the setup, the quantum efficiency of the SiPM was estimated to be 22% at the Xe wavelength of 178 nm. The low excess noise factor, high single photoelectron detection efficiency, and low bias voltage of SiPMs make them attractive alternative UV photon detection devices to photomultiplier tubes (PMTs) for liquid xenon detectors, especially for experiments requiring a very low energy detection threshold, such as neutralino dark matter searches

Impact of Cardiopulmonary Resuscitation on Cardiac Transplantation outcome

Introduction: Donor heart shortage limits heart transplantations programs while the number of patients waiting for cardiac transplant continues to increase. Optimizing the use of all available donor hearts is a vital key to reduce waiting list mortality. Among different extended criteria, prolong cardiopulmonary resuscitation (CPR), i.e. more than 20 min, has been considered under doubt to be a selection criterion in donor selection. The aim of this study was to compare the outcomes of heart transplantation from cardiopulmonary-resuscitated donors to those who received hearts from donors who did not require cardiopulmonary resuscitation.Methods: This study was a retrospective analysis of adult heart transplantation program in Masih Daneshvari Hospital in Tehran, Iran from 2010 to 2019. Donors and recipients’ demographics, cause of end-stage heart disease and brain death, duration of hospitalization for both donors and recipients and also the duration of cardiopulmonary resuscitation and other factors related to it were investigated. Qualitative variables were compared using Chi-square test. Quantitative variables were compared using T-test. Patient and graft survival rates were calculated using the actuarial method and compared using Wilcoxon's test.Results: Among 92 recipients, 39 were transplanted with cardiac grafts from CPR-suffering donors. There were no significant differences regarding sex, age, donor and recipient hospitalization periods, early rejection and 1-year-survival rate considering CPR and non-CPR grafts. However, we detected a strong negative correlation between the duration of CPR and 3-year-survival rate (P = 0.02 and R-value = -0.62) and also its association with post-transplant arrhythmias (P = 0.04).Conclusion: There is a negative possible influence of long-lasting CPRs (especially more than 20 minutes) in midterm survival and post-transplant complications

Performance of a cryogenic system prototype for the XENON1T Detector

We have developed an efficient cryogenic system with heat exchange and associated gas purification system, as a prototype for the XENON1T experiment. The XENON1T detector will use about 3 ton of liquid xenon (LXe) at a temperature of 175K as target and detection medium for a dark matter search. In this paper we report results on the cryogenic system performance focusing on the dynamics of the gas circulation-purification through a heated getter, at flow rates above 50 Standard Liter per Minute (SLPM). A maximum flow of 114 SLPM has been achieved, and using two heat exchangers in parallel, a heat exchange efficiency better than 96% has been measured

Characterization of the Hamamatsu S8664 Avalanche Photodiode for X-Ray and VUV-light detection

We present the first operation of the Avalanche Photodiode (APD) from Hamamatsu to xenon scintillation light and to direct X-rays of 22.1 keV and 5.9 keV. A large non-linear response was observed for the direct X-ray detection. At 415 V APD bias voltage it was of about 30 % for 22.1 keV and about 45 % for 5.9 keV. The quantum efficiency for 172 nm photons has been measured to be 69 +/- 15 %.Comment: 11 pages, 3 figures, submitted to Elsevie

Design and Performance of the XENON10 Dark Matter Experiment

XENON10 is the first two-phase xenon time projection chamber (TPC) developed within the XENON dark matter search program. The TPC, with an active liquid xenon (LXe) mass of about 14 kg, was installed at the Gran Sasso underground laboratory (LNGS) in Italy, and operated for more than one year, with excellent stability and performance. Results from a dark matter search with XENON10 have been published elsewhere. In this paper, we summarize the design and performance of the detector and its subsystems, based on calibration data using sources of gamma-rays and neutrons as well as background and Monte Carlo simulations data. The results on the detector's energy threshold, energy and position resolution, and overall efficiency show a performance that exceeds design specifications, in view of the very low energy threshold achieved (<10 keVr) and the excellent energy resolution achieved by combining the ionization and scintillation signals, detected simultaneously