Energy Calibration of the JLab Bremsstrahlung Tagging System

In this report, we present the energy calibration of the Hall B bremsstrahlung tagging system at the Thomas Jefferson National Accelerator Facility. The calibration was performed using a magnetic pair spectrometer. The tagged photon energy spectrum was measured in coincidence with $e^+e^-$ pairs as a function of the pair spectrometer magnetic field. Taking advantage of the internal linearity of the pair spectrometer, the energy of the tagging system was calibrated at the level of $\pm 0.1$. The absolute energy scale was determined using the $e^+e^-$ rate measurements close to the end-point of the photon spectrum. The energy variations across the full tagging range were found to be $<3$ MeV.Comment: 15 pages, 12 figure

The Heavy Photon Search test detector

The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment\u27s technical feasibility and to confirm that the trigger rates and occupancies are as expected. This paper describes the HPS Test Run apparatus and readout electronics and its performance. In this setting, a heavy photon can be identified as a narrow peak in the e(+)e(-) invariant mass spectrum above the trident background or as a narrow invariant mass peak with a decay vertex displaced from the production target, so charged particle tracking and vertexing are needed for its detection. In the HPS Test Run, charged particles are measured with a compact forward silicon microstrip tracker inside a dipole magnet. Electromagnetic showers are detected in a PbW0(4) crystal calorimeter situated behind the magnet, and are used to trigger the experiment and identify electrons and positrons. Both detectors are placed close to the beam line and split top bottom. This arrangement provides sensitivity to low mass heavy photons, allows clear passage of the unscattered beam, and avoids the spray of degraded electrons coming from the target. The discrimination between prompt and displaced e(+)e(-) pairs requires the first layer of silicon sensors be placed only 10 cm downstream of the target. The expected signal is small, and the trident background huge, so the experiment requires very large statistics. Accordingly, the HPS Test Run utilizes high-rate readout and data acquisition electronics and a fast trigger to exploit the essentially 100% duty cycle of the CEBAF accelerator at JLab. (C) 2014 The Authors. Published by Elsevier B.V

The Heavy Photon Search Test Detector

The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment׳s technical feasibility and to confirm that the trigger rates and occupancies are as expected. This paper describes the HPS Test Run apparatus and readout electronics and its performance. In this setting, a heavy photon can be identified as a narrow peak in the e+ e− invariant mass spectrum above the trident background or as a narrow invariant mass peak with a decay vertex displaced from the production target, so charged particle tracking and vertexing are needed for its detection. In the HPS Test Run, charged particles are measured with a compact forward silicon microstrip tracker inside a dipole magnet. Electromagnetic showers are detected in a PbW04 crystal calorimeter situated behind the magnet, and are used to trigger the experiment and identify electrons and positrons. Both detectors are placed close to the beam line and split top-bottom. This arrangement provides sensitivity to low-mass heavy photons, allows clear passage of the unscattered beam, and avoids the spray of degraded electrons coming from the target. The discrimination between prompt and displaced e+ e− pairs requires the first layer of silicon sensors be placed only 10 cm downstream of the target. The expected signal is small, and the trident background huge, so the experiment requires very large statistics. Accordingly, the HPS Test Run utilizes high-rate readout and data acquisition electronics and a fast trigger to exploit the essentially 100% duty cycle of the CEBAF accelerator at JLab

Search for a Dark Photon in Electroproduced e + e − pairs with the Heavy Photon Search experiment at JLab

The Heavy Photon Search experiment took its first data in a 2015 engineering run using a 1.056 GeV, 50 nA electron beam provided by CEBAF at the Thomas Jefferson National Accelerator Facility, searching for a prompt, electroproduced dark photon with a mass between 19 and 81  MeV/c2. A search for a resonance in the e+e− invariant mass distribution, using 1.7 days (1170  nb−1) of data, showed no evidence of dark photon decays above the large QED background, confirming earlier searches and demonstrating the full functionality of the experiment. Upper limits on the square of the coupling of the dark photon to the standard model photon are set at the level of 6×10−6. Future runs with higher luminosity will explore new territory

О РАСПРЕДЕЛЕНИИ ЗНАЧЕНИЙ НЕПОЛНЫХ СУММ ГАУССА

The theorems on the distribution of absolute values incomplete Gauss sums are proved. Asymptotic formulas of the fractional moments of incomplete Gauss sums are proved.Доказана теорема о распределении значений неполных сумм Гаусса. Получены асимптотические формулы для дробных моментов этих сумм

Meglumine Sodium Succinate to Correct COVID-19-Associated Coagulopathy: the Feasibility Study

Aim of the study: to evaluate the effect of meglumine sodium succinate (MSS) on the efficacy of anticoagulant therapy in patients with severe COVID-19 infection complicated by bilateral community-acquired pneumonia.Materials and methods. Overall efficacy of treatment was analyzed in 12 patients hospitalized to ICU with the diagnosis of severe confirmed COVID-19 coronavirus infection (U07.1) complicated by bilateral multisegmental pneumonia. All patients received prophylactic anticoagulation with unfractionated heparin. The patients were divided into two groups: 7 of them received a multi-electrolyte solution containing MSS 5 ml/kg daily for the entire ICU stay (3-10 days) as a part of therapy; 5 patients received a similar volume of a conventional multi-electrolyte solution containing no metabolically active substrates and comprised a control group. Coagulation parameters were measured in arterial and venous blood of all patients at the following stages: 1) upon admission to the ICU; 2) 2-4 hours after the first dose of heparin; 3) 8-12 hours after the second dose of heparin; 4) 24 hours after the beginning of intensive therapy. On the 28th day of follow-up, mortality, duration of ICU stay, and incidence of thrombotic complications in the groups were evaluated. Nonparametric methods of statistical analysis were used to assess intragroup changes and intergroup differences.Results. The group of patients administered with MSS had significantly fewer thromboembolic events during 28 days of treatment and shorter ICU stay. These patients responded faster to anticoagulant therapy, which was suggested by more distinct changes in coagulation parameters, i.e. increased APTT, persisting viable thrombocyte population, reduced D-dimer and fibrinogen levels.Conclusion. The metabolic action of succinate possibly increases endothelial resistance to damaging factors and reduces its procoagulant activity. The hypothesis requires testing in a larger clinical study with a design including laboratory evaluation of the efficacy of varying doses of the studied drug as well as aiming at elucidation of the mechanisms of its effect on specific pro- and anticoagulation system components

The Heavy Photon Search test detector

The Heavy Photon Search (HPS), an experiment to search for a hidden sector photon in fixed target electroproduction, is preparing for installation at the Thomas Jefferson National Accelerator Facility (JLab) in the Fall of 2014. As the first stage of this project, the HPS Test Run apparatus was constructed and operated in 2012 to demonstrate the experiment׳s technical feasibility and to confirm that the trigger rates and occupancies are as expected. This paper describes the HPS Test Run apparatus and readout electronics and its performance. In this setting, a heavy photon can be identified as a narrow peak in the e+e− invariant mass spectrum above the trident background or as a narrow invariant mass peak with a decay vertex displaced from the production target, so charged particle tracking and vertexing are needed for its detection. In the HPS Test Run, charged particles are measured with a compact forward silicon microstrip tracker inside a dipole magnet. Electromagnetic showers are detected in a PbW04 crystal calorimeter situated behind the magnet, and are used to trigger the experiment and identify electrons and positrons. Both detectors are placed close to the beam line and split top-bottom. This arrangement provides sensitivity to low-mass heavy photons, allows clear passage of the unscattered beam, and avoids the spray of degraded electrons coming from the target. The discrimination between prompt and displaced e+e− pairs requires the first layer of silicon sensors be placed only 10 cm downstream of the target. The expected signal is small, and the trident background huge, so the experiment requires very large statistics. Accordingly, the HPS Test Run utilizes high-rate readout and data acquisition electronics and a fast trigger to exploit the essentially 100% duty cycle of the CEBAF accelerator at JLab

ВОЗМОЖНОСТИ ТЕРАПИИ ГЕМОРРАГИЧЕСКОГО ШОКА У БОЛЬНЫХ С ЖЕЛУДОЧНО-КИШЕЧНЫМ КРОВОТЕЧЕНИЕМ

Objective: to evaluate the antihypoxic effect of Mexicor in patients with gastrointestinal bleeding of ulcerative etiology. Materials and methods. The paper presents the materials obtained during the treatment of 53 patients with nonvaricose gastrointestinal bleeding who were hospitalized with grades II—III hemorrhagic shock. Results. Incorporation of Mexicor into the comprehensive program for the intensive therapy of acute gastrointestinal bleeding was ascertained to reduce the activity of prooxidant processes, and the manifestations of tissue hypoxia and systemic inflammation and to improve systemic hemodynamic parameters and the clinical course of an early posthemorrhagic period. Conclusion. The use of Mexicor in patients with gastric bleeding reduces the number of complications and the duration of treatment in the intensive care unit.  Цель исследования — оценить противогипоксическое и антиоксидантное действие Мексикора у больных с желудочно-кишечными кровотечениями язвенной этиологии. Материалы и методы. В статье представлены материалы, полученные в процессе лечения 53 больных язвенной болезнью с неварикозными желудочно-кишечными кровотечениями, госпитализированными в состоянии геморрагического шока II—III ст. Результаты. Установлено, что включение Мексикора в комплексную программу интенсивной терапии острых желудочно-кишечных кровотечений снижает в организме больных активность прооксидантных процессов, выраженность проявлений тканевой гипоксии и системного воспаления, улучшает показатели системной гемодинамики и клиническое течение раннего постгеморрагического периода. Заключение. Применение Мексикора у пациентов с желудочными кровотечениями снижает число осложнений, сокращает длительность лечения больных в отделении реанимации.

Searching for Prompt and Long-Lived Dark Photons in Electroproduced e⁺ e⁻ Pairs with the Heavy Photon Search Experiment at JLab

The heavy photon search experiment (HPS) at the Thomas Jefferson National Accelerator Facility searches for electroproduced dark photons. We report results from the 2016 engineering run consisting of 10 608  nb−1 of data for both the prompt and displaced vertex searches. A search for a prompt resonance in the e+e− invariant mass distribution between 39 and 179 MeV showed no evidence of dark photons above the large QED background, limiting the coupling of ε2≳10−5, in agreement with previous searches. The search for displaced vertices showed no evidence of excess signal over background in the masses between 60 and 150 MeV, but had insufficient luminosity to limit canonical heavy photon production. This is the first displaced vertex search result published by HPS. HPS has taken high-luminosity data runs in 2019 and 2021 that will explore new dark photon phase space

Large-angle production of charged pions by 3 GeV/c - 12.9 GeV/c protons on beryllium, aluminium and lead targets

Measurements of the double-differential $\pi^{\pm}$ production cross-section in the range of momentum 100 \MeVc \leq p < 800 \MeVc and angle 0.35 \rad \leq \theta < 2.15 \rad in proton--beryllium, proton--aluminium and proton--lead collisions are presented. The data were taken with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 \GeVc to 12.9 \GeVc hitting a target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was performed using a small-radius cylindrical time projection chamber (TPC) placed inside a solenoidal magnet. Incident particles were identified by an elaborate system of beam detectors. Results are obtained for the double-differential cross-sections at six incident proton beam momenta (3 \GeVc, 5 \GeVc, 8 \GeVc, 8.9 \GeVc (Be only), 12 \GeVc and 12.9 \GeVc (Al only)) and compared to previously available data