A tagged low-momentum kaon test-beam exposure with a 250L LAr TPC (J-PARC T32)

Abstract

At the beginning of 2010, we presented at the J-PARC PAC an R&D program towards large (100 kton scale) liquid argon TPCs, suitable to investigate, in conjunction with the J-PARC neutrino beam, the possibility of CP violation in the neutrino sector and to search for nucleon decay. As a first step we proposed a test experiment to identify and measure charged kaons, including their decays, in liquid argon. The detector, a 250L LAr TPC, is exposed to charged kaons, in a momentum range of 540 − 800 MeV/c, in the K1.1BR beamline of the J-PARC slow extraction facility. This is especially important to estimate efficiency and background for nucleon decay searches in the charged kaon mode (p → νK + , etc.), where the kaon momentum is expected to be in the few hundred MeV/c range. A prototype setup has been exposed in the K1.1BR beamline in the fall of 2010. This paper describes the capabilities of the beamline, the construction and setting up of the detector prototype, along with some preliminary results.

Future liquid Argon detectors

“…The ability to reproduce well the dE/dx performance has been demonstrated with a 250 L chamber exposed to a tagged low-momentum kaon test-beam at J-PARC [21]. Figure 6 shows the dE/dx response measured with the 250 L chamber exposed to the tagged low-momentum kaon test-beam at J-PARC.…”

Status and New Ideas Regarding Liquid Argon Detectors

“…At the J-PARC facility, a 250-liter LAr TPC [149] has been exposed to a 500 − 800 MeV hadron beam, enriched in kaons. This test will provide particle identification capabilities in a LAr TPC through the measurement of specific ionization versus residual range for pions, protons, and kaons.…”

First operation and drift field performance of a large area double phase LAr Electron Multiplier Time Projection Chamber with an immersed Greinacher high-voltage multiplier

“…The system has never been damaged even though a few discharges occurred while testing several different Greinacher circuits. A software to control the AC power supply unit was built based on LabView 5 . It has a graphical interface as shown in Figure 7, where one can type in the set value for the peak-to-peak output voltage and can start/stop charging by pressing a button.…”

“…This significantly improves 2012 JINST 7 P08026 the event reconstruction quality with a lower energy deposition threshold and a better resolution per volumetric pixel (voxel) compared to a conventional single-phase LAr-TPC [2], such as e.g. ICARUS [3], ArgoNeut [4] or J-PARC T32 [5]. In addition the charge amplification compensates for potential loss of signal-to-noise due to the charge diffusion and attachment to electronegative impurities diluted in LAr, which both become more important as the drift length increases.…”

“…The main advantages of the Greinacher HV multiplier are: (1) all the HV parts are immersed in LAr which has a large dielectric strength (∼1 MV/cm), (2) thus feedthroughs for very HV are not needed,(3) the circuit itself can provide all the stages needed to create a uniform field, thus the system has no resistive load, (4) thus the power dissipation is virtually zero and (5) this allows a low frequency (e.g. 50 Hz) of the AC input signal which is fully outside of the bandwidth of the charge amplifiers used for this type of detectors.…”