52244461
Design and operation of ARGONTUBE: a 5 m long drift liquid argon TPC
The Liquid Argon Time Projection Chamber (LArTPC) is a prime type of detector for future large-mass neutrino observatories and proton decay searches. In this paper we present the design and operation, as well as experimental results from ARGONTUBE, a LArTPC being operated at the AEC-LHEP, University of Bern. The main goal of this detector is to prove the feasibility of charge drift over very long distances in liquid argon. Many other aspects of the LArTPC technology are also investigated, such as a voltage multiplier to generate high voltage in liquid argon (Greinacher circuit), a cryogenic purification system and the application of multi-photon ionization of liquid argon by a UV laser. For the first time, tracks induced by cosmic muons and UV laser beam pulses have been observed and studied at drift distances of up to 5 m, the longest reached to date.
110883987
30 kV coaxial vacuum-tight feedthrough for operation at cryogenic temperatures
In this paper we describe the technology of building a vacuum-tight high voltage feedthrough which is able to operate at voltages up to 30 kV. The feedthrough has a coaxial structure with a grounded sheath which makes it capable to lead high voltage potentials into cryogenic liquids, without risk of surface discharges in the gas phase above the liquid level. The feedthrough is designed to be used in ionization detectors, based on liquefied noble gases, such as Argon or Xenon.
118548096
Measurement of the two-photon absorption cross-section of liquid argon with a time projection chamber
This paper reports on laser-induced multiphoton ionization at 266?nm of liquid argon in a time projection chamber (LAr TPC) detector. The electron signal produced by the laser beam is a formidable tool for the calibration and monitoring of next-generation large-mass LAr TPCs. The detector that we designed and tested allowed us to measure the two-photon absorption cross-section of LAr with unprecedented accuracy and precision: ?ex=(1.24?0.10stat?0.30syst)?10? 56?cm4?s? 1.
98478755
Monitoring the parameters of a large size liquid Argon Time Projection Chamber using UV laser beams
This paper reports on multiphoton ionization at 266 nm of liquid Argon in a Time Projection Chamber (LAr TPC) detector. The electron signal produced by the laser beam is a formidable tool for the monitoring of the next generation large mass LAr TPCs [1]. The detector we have designed and tested allowed us also to measure the two-photon absorption cross-section (σex) of LAr with unprecedented accuracy and precision, appropriate for using the UV laser technique also for a quantitative calibration of the detector.
118084361
Calibration and analysis of the 2007 data
he physics program of the NA61/SHINE (SHINE = SPS Heavy Ion and Neutrino Experiment) experiment at the CERN SPS consists of three subjects. In the first stage of data taking (2007-2009) measurements of hadron production in hadron-nucleus interactions needed for neutrino (T2K) and cosmic-ray (Pierre Auger and KASCADE) experiments will be performed. In the second stage (2009-2010) hadron production in proton-proton and proton-nucleus interactions needed as reference data for a better understanding of nucleus-nucleus reactions will be studied. In the third stage (2009-2013) energy dependence of hadron production properties will be measured in p+p, p+Pb interactions and nucleus-nucleus collisions, with the aim to identify the properties of the onset of deconfinement and find evidence for the critical point of strongly interacting matter. The NA61 experiment was approved at CERN in June 2007. The first pilot run was performed during October 2007. Calibrations of all detector components have been performed successfully and preliminary uncorrected spectra have been obtained. High quality of track reconstruction and particle identification similar to NA49 has been achieved. The data and new detailed simulations confirm that the NA61 detector acceptance and particle identification capabilities cover the phase space required by the T2K experiment. This document reports on the progress made in the calibration and analysis of the 2007 data.
119265780
Ionization signals from electrons and alpha-particles in mixtures of liquid Argon and Nitrogen – perspectives on protons for Gamma Resonant Nuclear Absorption applications
In this paper we report on a detailed study of ionization signals produced by Compton electrons and alpha-particles in a Time Projection Chamber (TPC) filled with different mixtures of liquid Argon and Nitrogen. The measurements were carried out with Nitrogen concentrations up to 15% and a drift electric field in the range 0-50 kV/cm. A prediction for proton ionization signals is made by means of interpolation. This study has been conducted in view of the possible use of liquid Ar−N2 TPCs for the detection of gamma-rays in the resonant band of the Nitrogen absorption spectrum, a promising technology for security and medical applications.
120635227
Cosmic-Ray Theory
197448895
ENERGY SPECTRUM AND STRUCTURE OF LARGE AIR SHOWERS
Nineteen 3.3-m/sup 2/ plastic scintillation detectors in a hexagonal array covering 2 km/sup 2/ were used in this study. Methods of recording and analyzing data are discussed, and results are presented on the following: lateral distribution of particle density, the proportion of penetrating particles, variation of shower intensity and shower size with atmospheric depth, the primary cosmic ray energy spectrum, isotropy of primary cosmic radiation, and the largest shower recorded. (A.G.W.)
272273
Further Measurements on the Disintegration Curve of Mesotrons
'HE authors of the present paper have recently described a method for the experimental determination of the disintegration curve of Tnesotrons and have given a preliminary account of the results obtained. ' The method has been since improved and a new and more extensive set of data has been taken. A summary of the riew results is presented here. The experimental arrangement, which is similar in principle to that used in the previous experiment, is schematically represented in Fig. 1. The three counters L are in parallel, and so are the four counters 8 and the five counters JI. Counters A, ~, A2, and 8 feed into the "time circuit" T; this circuit gives a pulse whose amplitude is a function of the time delay between a coincidence A &A2 and the subsequent pulse of 8. Counters L, A1, A~, 8, and M feed into an anticoincidence circuit C, which records the anticoincidences LA1A28 —2VI, i.e. , the coincidences between LA1A2 and 8 which are not accompanied by a pulse in lK The recording circuit R operates a pen writing instrument in such a way that the pulse from the time circuit is recorded only when it is accompanied by a pulse from the anticoincidence circuit. The events which one desires to record are of the following type. A mesotron traverses the counters L, A1, and A &, is stopped in the absorber A, and then disintegrates giving rise to an electron which discharges one of counters B.The amplitude of the pulse from the time circuit, as recorded by the pen writing instrument, gives a measure of the life span of the mesotron in the absorber. In addition to the records representing disintegration events, records will be obtained whenever
119999230
Early days in cosmic rays
Early in 1928, shortly after receiving my PhD at the University of Bologna, I was offered the position of assistant at the Physics Institute of the University of Florence. The Institute rose among olive trees, on the hill of Arcetri, a short distance from the villa where Galileo had spent the last years of his life as a political exile. The chair of physics was held by Professor Antonio Garbasso who, in earlier years, had done some creditable scientific work. But the first world war and subsequent events had diverted his interests toward politics. He was now a senator and the mayor of Florence. However, he still went to Arcetri three times a week to deliver his lectures, and he still had a strong desire to see the Institute, which he had built, become an important center of research.
122227593
Evidence for x Rays From Sources Outside the Solar System
Data from an Aerobee rocket carrying three large-area geiger counters have revealed a considerable flux of radiation in the night sky. Analysis of these data indicates the bulk of the radiation is soft x rays from sources outside the solar system. Synchrotron radiation by cosmic electrons is a possible mechanism for the production of these x rays. Ordinary stellar sources could also contribute a considerable fraction of the observed radiation. (H.D.R.)