Studies of a Liquid Argon Time Projection Chamber in a Magnetic Field A Proposal to the DOE Advanced Detector Research Program

The recent dramatic success of the ICARUS 300-ton liquid-argon time-projection-chamber prototype [1] indicates that it is timely to review the possibilities for large-scale application of this technology for accelerator-based neutrino physics, neutrino astrophysics, and proton decay [2]. A full exploration of the MNS neutrino mixing matrix (and extensions if sterile neutrinos exist) should be possible if the large mixing angle MSW solution to the solar neutrino problem presently favored by the data [3] is confirmed by futures measurements. A large detector for this purpose should be able to distinguish the charge of the lepton into which the neutrino converts, for which the detector should be immersed in a magnetic field. The most promising option for a large detector that can distinguish the charge of an electron is magnetized liquid argon [4, 5]. However, all studies to date of liquid argon detectors suitable for neutrino physics [6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17] have been in zero magnetic field. We propose to study two key issues for a large magnetized liquid argon detector: 1. Verification that a liquid argon detector can be operated with the electric field perpendicular to the magnetic field (unlike gas phase time projection chambers that must be operated with E parallel to B). 2. Verification that a liquid argon detector can be operated at several atmospheres pressure, as would occur near the bottom of a very large detector. These studies are to be performed with a small detector, similar to that used to measure the electron lifetime in liquid argon [9, 10, 11, 18]. The requested funds for this are $30k. This study will be followed by a larger (by at least an order of magnitude) effort to demonstrate the accuracy of electron charge determination as a function of electron energy in a beam test [19]. Corresponding author: [email protected]