The committee for the study of the extension of the Hadron Experimental Facility was formed under the Hadron Hall Users Association in August, 2015. This document is a summary of the discussions among the committee members, and documented by a part of the members listed below.
This write-up document is a summary of International workshop on the project for the extended hadron experimental facility which was held from March 26 to 28, 2018 at KEK Tokai Campus. This document is a collection of Letter Of Intents (LOIs) related
to the proposed beam lines in the extended hadron experimental facility at J-PARC.
In order to explore CP asymmetry in the lepton sector, a power upgrade to the neutrino experimental facility at J-PARC is a key requirement for both the Tokai to Kamioka (T2K) long-baseline neutrino oscillation experiment and a future project with Hy
per-Kamiokande. Based on five years of operational experience, the facility has achieved stable operation with 230 kW beam power without significant problems on the beam-line apparatus. After successful maintenance works in 2013-2014 to replace all electromagnetic horns and a production target, the facility is now ready to accomodate a 750-kW-rated beam. Also, the possibility of achieving a few to multi-MW beam operation is discussed in detail.
Discussions in the taskforce meetings in the period of Jan.-Mar. 2009 on the technical possibility of the ultracold neutron (UCN) source at the Japan Proton Accelerator Research Complex (J-PARC) is summarized.
With an appropriate hard scale, exclusive hadronic processes could provide novel information of the internal quark-gluon configurations of hadrons. The availability of 10-20 GeV secondary meson beam in the coming high-momentum beam line of Hadron Hal
l at J-PARC offers an unique opportunity to carry out the measurements of the exclusive hard processes. We address this interesting approach by two possibilities: (a) $pi^- p to K^0 Lambda(1405)$ for the constituent quark structure of $Lambda(1405)$, and (b) exclusive pion-induced Drell-Yan process $pi^- p to gamma^* n to l^+ l^- n$ for the generalized parton distributions (GPDs) of nucleons. Realization of such measurements at J-PARC will open up a new way of accessing the internal quark structure of exotic hadrons and also the nucleon GPDs based on a solid theoretical foundation of perturbative QCD.
On April 2015, the J-PARC E56 (JSNS2: J-PARC Sterile Neutrino Search using neutrinos from J-PARC Spallation Neutron Source) experiment officially obtained stage-1 approval from J-PARC. We have since started to perform liquid scintillator R&D for impr
oving energy resolution and fast neutron rejection. Also, we are studying Avalanche Photo-Diodes (SiPM) inside the liquid scintillator. In addition to the R&D work, a background measurement for the proton beam bunch timing using a small liquid scintillator volume was planned, and the safety discussions for the measurement have been done. This report describes the status of the R&D work and the background measurements, in addition to the milestones required before stage-2 approval.