Search for sub-millicharged particles at J-PARC

Abstract

We studied the feasibility of an experiment searching for sub-millicharged particles (χs) using 30 GeV proton fixed-target collisions at J-PARC. The detector is composed of two layers of stacked scintillator bars and PMTs and is proposed to be installed 280 m from the target. The main background is a random coincidence between two layers due to dark counts in PMTs, which can be reduced to a negligible level using the timing of the proton beam. With NPOT = 1022 which corresponds to running the experiment for three years, the experiment provides sensitivity to χs with the charge down to 5 × 10−5 in mχ< 0.2 GeV/c2 and 8 × 10−4 in mχ< 1.6 GeV/c2. This is the regime largely uncovered by previous experiments. We also explored a few detector designs to achieve optimal sensitivity to χs. The photoelectron yield is the main driver, but the sensitivity does not have a strong dependence on detector configuration in the sub-millicharge regime.

FACET: a new long-lived particle detector in the very forward region of the CMS experiment

“…There are several proposed high-luminosity LHC (HL-LHC) era experiments targeting LLP searches, such as MATHUSLA [24,25], CODEX-b [26], FASER-2 [27,28], ANUBIS [29], FORMOSA [30]; as well as SHADOWS [31], a beam-dump experiment at the CERN SPS. There are also experimental proposals outside CERN, such as SUBMET [32] at J-PARC and LUXE [33] at the DESY XFEL facility.…”

FLArE up dark sectors with EM form factors at the LHC Forward Physics Facility

“…When compared with future projections, although the FORMOSA detector [12] to operate in the FPF is the leading proposal based on its projection, the FLArE search based on electron scatterings could provide an independent measurement method for a wide range of masses for mCP with charges O(10 −3 -10 −1 ). It can also have better sensitivity in the mass range above ∼ 4 GeV than proposed FerMINI [38] and SUBMET [118,119] detectors. In the high-mass regime, FLArE is complementary to the sensitivity of milliQan [28][29][30][31], although it has a weaker sensitivity for m χ (40-50) GeV.…”

Search for sub-millicharged particles at J-PARC

“…Refer to Ref. [4] for details about the site and 𝜒s generation. If 𝜒s are produced, they will penetrate the space between the target and the detector without a significant energy loss because of their feeble interaction with matter.…”