A photograph taken at the counting room of K1.8 beam line of J-PARC (November 7, 2015).
パイロットE05実験時にJ-PARC K1.8 ビームラインの計測室で撮影した写真 (2015年11月)。


 A Ξ hypernucleus, 12ΞBe (a bound system of 11B and Ξ-) will be searched by the (K-,K+) reaction at the K1.8 beam line in J-PARC (J-PARC E05 Experiment).

 There were old measurements with the same reaction, 12C(K-,K+), at KEK and BNL. However, they could not find a clear evidence of a bound nuclear system with a Ξ- hyperon. In the J-PARC E05 experiment, we will install a newly designed magnetic spectrometer S-2S (Strangeeness -2 Spectrometer). The introduction of S-2S allows us to achieve the energy resolution of a few MeV FWHM in a resulting hypernuclear spectrum, which would be the most sensitive measurement for a detection of Ξ hypernuclei.

  A construction of the new spectrometer S-2S was completed. Detector commissioning is in progress. We are now developing an active fiber target.

Proposal (Status: Approved)

→ can be found at J-PARC's web page

Official Web Page


Personal Memos

Presentation files

S-2S Magnet

Magnetic Field Measurement of S-2S D (2015/2016)

TOF Detector


Aerogel Cherenkov Detector

Water Cherenkov Detector (WC)

Prototype WC test at ELPH (June 29-30, 2014)

Prototype WC test w/ cosmic ray (2014/2015)

New WC test w/ cosmic ray

Geant4 Simulation for one box of WC (July 21, 2015)

Bucking coil test of WC PMT (March 29, 2016)

MC Simulation for Achiebable Resolution of S-2S (August 25, 2014)

MC Simulation of Active Fiber Target (made in 2015, updated in 2018)

Transmission Measurement at Kyoto Univ. (March 19, 2015)


Seminar (multi-strangeness)



後神 利志
Toshiyuki Gogami, D. Sc.

022-795-6452 (Ex. 6452)