[en] A liquid argon total absorption detector with a very high number of sampling sections is described. Measurements of the collected charge and of its longitudinal distribution with 25 GeV ionizing particles have been performed, giving an energy resolution for electromagnetic showers limited by the residual sampling fluctuations. (Auth.)

[en] The response of a stainless steel/liquid argon sampling calorimeter has been studied with electrons from 20 to 40 GeV. Best conditions for the efficiency in ionization charge collection were found. An E-₁/₂ dependence of the relative energy resolution on the incident electron energy was found, which well interprets the experimental results. 4 refs

[en] Long liquid hydrogen targets have been designed in which the detection and measurement of the Vavilov-Cherenkov radiation, emitted from the charged incoming particle before the interaction, give a good estimate of the interaction point position. This allows a satisfactory degree of precision in the geometrical reconstruction of the event to be maintained. (orig./HSI)

No abstract available

[en] Results from neutrino oscillation experiments in the last ten years have revolutionized the field of neutrino physics. While the overall oscillation picture for three neutrinos is now well established and precision measurements of the oscillation parameters are underway, crucial issues remain. In particular, the hierarchy of the neutrino masses, the structure of the neutrino mixing matrix, and, above all, CP violation in the neutrino sector are the primary experimental challenges in upcoming years. A program that utilizes the newly commissioned NuMI neutrino beamline, and its planned upgrades, together with a high-performance, large-mass detector will be in an excellent position to provide decisive answers to these key neutrino physics questions. A Liquid Argon time projection chamber (LArTPC), which combines fine-grained tracking, total absorption calorimetry, and scalability, is well matched for this physics program. The few-millimeter-scale spatial granularity of a LArTPC combined with dE/dx measurements make it a powerful detector for neutrino oscillation physics. Scans of simulated event samples, both directed and blind, have shown that electron identification in ν_e charged current interactions can be maintained at an efficiency of 80%. Backgrounds for ν_e appearance searches from neutral current events with a π⁰ are reduced well below the ∼ 0.5-1.0% ν_e contamination of the ν_μ beam. While the ICARUS collaboration has pioneered this technology and shown its feasibility with successful operation of the T600 (600-ton) LArTPC, a detector for off-axis, long-baseline neutrino physics must be many times more massive to compensate for the low event rates. We have a baseline concept based on the ICARUS wire plane structure and commercial methods of argon purification and housed in an industrial liquefied-natural-gas tank. Fifteen to fifty kton liquid argon capacity tanks have been considered. A very preliminary cost estimate for a 50-kton detector is $100M (unloaded). Continuing Rand D will emphasize those issues pertaining to implementation of this very large scale liquid argon detector concept. Key hardware issues are achievement and maintenance of argon purity in the environment of an industrial tank, the assembly of very large electrode planes, and the signal quality obtained from readout electrodes with very long wires. Key data processing issues include an initial focus on rejection of cosmic rays for a surface experiment. E.orts are underway at Fermilab and a small number of universities in the US and Canada to address these issues with the goal of embarking on the construction of industrial-scale prototypes within one year. One such prototype could be deployed in the MiniBooNE beamline or in the NuMI surface building where neutrino interactions could be observed. These efforts are complementary to efforts around the world that include US participation, such as the construction of a LArTPC for the 2-km detector location at T2K. The 2005 APS neutrino study recommendations recognize that ''The development of new technologies will be essential for further advances in neutrino physics''. In a recent talk to EPP2010, Fermilab director P. Oddone, discussing the Fermilab program, states on his slides: ''We want to start a long term Rand D program towards massive totally active liquid Argon detectors for extensions of NOvA''. [8]. As such, we are poised to enlarge our Rand D efforts to realize the promise of a large liquid argon detector for neutrino physics

[en] The performance of a fine grain liquid argon calorimeter with aluminium electrodes has been studied. Measurements have been performed with 13.3-35 GeV/c electrons, muons and pions. The fine sampling structure and the large fraction of active absorber in this detector allowed an energy resolution for electrons of sigma(E)/E=[(0.08/E)²+(-.036/√E)²]sup(1/2) to be reached. The space and angular resolutions for electromagnetic showers can be represented as sigma(x)=[(38.5/E)²+(12.8/√E)²]sup(1/2) mm and sigma(theta)=[(87.3/E)²+(33.8/√E)²]sup(1/2) mrad. Due to the detailed measurements of the shower development a good electron/hadron discrimination is achieved. The low noise allows also the detection and identification of muons. (orig./HSI)

[en] The Large Electron Multipliers (LEMs) are key components of double phase liquid argon TPCs. The drifting charges after being extracted from the liquid are amplified in the LEM positioned half a centimeter above the liquid in pure argon vapor at 87 K. The LEM is characterised by the size of its dielectric rim around the holes, the thickness of the LEM insulator, the diameter of the holes as well as their geometrical layout. The impact of those design parameters on the amplification were checked by testing seven different LEMs with an active area of 10×10 cm"2 in a double phase liquid argon TPC of 21 cm drift. We studied their response in terms of maximal reachable gain and impact on the collected charge uniformity as well as the long-term stability of the gain. We show that we could reach maximal gains of around 150 which corresponds to a signal-to-noise ratio (S/N) of about 800 for a minimal ionising particle (MIP) signal on 3 mm readout strips. We could also conclude that the dielectric surfaces in the vicinity of the LEM holes charge up with different time constants that depend on their design parameters. Our results demonstrate that the LAr LEM TPC is a robust concept that is well-understood and well-suited for operation in ultra-pure cryogenic environments and that can match the goals of future large-scale liquid argon detectors

No abstract available

[en] Voltages above a hundred kilo-volt will be required to generate the drift field of future very large liquid Argon Time Projection Chambers. One of the most delicate component is the feedthrough whose role is to safely deliver the very high voltage to the cathode through the thick insulating walls of the cryostat without compromising the purity of the argon inside. This requires a feedthrough that is typically meters long and carefully designed to be vacuum tight and have small heat input. Furthermore, all materials should be carefully chosen to allow operation in cryogenic conditions. In addition, electric fields in liquid argon should be kept below a threshold to reduce risks of discharges. The combination of all above requirements represents significant challenges from the design and manufacturing perspective. In this paper, we report on the successful operation of a feedthrough satisfying all the above requirements. The details of the feedthrough design and its manufacturing steps are provided. Very high voltages up to unprecedented voltages of −300 kV could be applied during long periods repeatedly. A source of instability was observed, which was specific to the setup configuration which was used for the test and not due to the feedthrough itself.

[en] We propose a scalable line of liquid argon TPC detectors based on a three dimensional cubic frame array immersed in a common liquid argon volume. The paper describes general lines, main construction criteria, crucial points, parameters and required preliminary R and D activities for the construction of detectors with active mass ranging from 200 ton to 100 kTon. Such detectors appear as unique for supernova detection, proton decay, LBL neutrino physics and other astropaticle physics applications