J-PARC Hadron Experimental Facility has been constructed in its size as half as the original plan and has started its beam operations. The users have been discussing to realize the extension of the Hadron Experimental Facility since the begining of the construction.
The Hadron Experimental Facility -- present and future
The current Hadron Experimental facility corresponds to the left part of the picture.
The size of the current hall is as half as that of the one in the 3D image.
The 30GeV primary proton beam from the Main Ring (MR) is bombereded on a production target (T1),
and produced secondary particles are transported to secondary beam lines (K1.8, K1.8BR, and KL).
A fraction of the primary proton beam is transported into a primary proton beam line (High-p).
The primary proton beam can also be transported to COMET. Hihg-p beam line finished its construction in
2019. The COMET beam line is being constructed.
The beam lines available (or soon to be avilable) are:
- Charged particle beam lines(K1.8, K1.8BR)
The beam lines provide mass-separated charged particle beams using electrostatic separators.
K1.8 beam line provides particles with a momentum of up to 2.0 GeV/c.
The main focus of the K1.8 beam line is the hypernuclear physics with two strangeness using 1.8GeV/c high-intensity K- beam.
K1.8BR beam line is branched from K1.8 in the middle. The research in K1.8BR includes Kaonic nucleus study using 1.0 GeV/c K- beam. K1.8 and K1.8BR cannot be operated simultaneously as they shares the upstream of the beam line.
- Neutral Kaon beam line(KL)
The KL beam line provides high-intensity neutral kaon beam to KOTO experiment, which is to search for new physics beyon the standard model
by observing a kaon rare decay that is KL → π0 ν νbar.
- High-p beam line
The high-p beam line provides 30GeV primary proton beam to the E16 experiment.
The E16 experiment is to measure in-medium spectral change of vector mesons to
study the spontaneous breaking of chiral symmetry, which is expected to generate a majority of the hadron mass.
The beam line upgrade is planned to provide high-momentum secondary beams with a momentum of up to 20 GeV/c and conduct hadron physics.
- COMET beam line
The COMET beam line provides 8GeV proton beam, producing tremendous amount of muons for the COMET experiment. The experiment aims at observing a lepton flavor violating process
called the electron-muon conversion, to search for new physics beyond the standard model.
Extension Project of Hadron Experimental Facility
We plan to extend the hadron experimental facility, installing a new production target (T2) and building new secondary beam lines (K1.1/K1.1BR, HIHR, KL and K10).
The beam lines to be constructed are:
- K1.1/K1.1BR beam lines
The K1.1/K1.1BR beam line provides low momentum K- beams with 0.8-1.2GeV/c.
The planned physics programs include
single strangeness hypernuclear physics, hyperon scattering experiment, and kaonic nucleus study.
The beam line's main focuses are on the understainding of the baryon-baryon forces (nuclear forces),
and the baryon proerties inside nucleus.
- HIHR (High-intensity high-resolution) beam line
High intensity charged pion beam with a momentum of up to 2 GeV/c is provided.
Measurement of hyper-nuclear level-strucutre with ten times higer resolution
can be achieved by the dispersion matching method.
The main focus of the beam line is to understand baryon-baryon forces (nuclear forces) inside dense nucleus/hadronic matter to elucidate the mystery of the inner structure of the nuetron stars.
- New KL beam line
High-intensity neutral kaon beam is provided.
The Beam extraction is 5 degrees in the new KL, while it is 16 degrees in the current KL. The change minimizes neutron background fraction, and increases the intensity by a factor of five. The new KOTO experiment will search for the rare kaon decay with 100 times higher sentsitivity.
- K10 beam line
Mass-separated high momentum charged particles (K, pi, and anti-p) with a momentum of (2-10GeV/c) are provided.
Spectroscopy of hadrons with two or three strangeness and charmed baryons is conducted to study the effective degree of freedom that describe hadrons, such as diquark correlation, and the properties of hadrons inside nucleus.
- Test beam line (Test BL）
The test beam line provides charged particle beams for detector tests,
after the old KL area is evacuated.
Focused Review
"Review of Hadron Experimental Facility Extension (HEF-EX)"(2021/8/10,11,17,25, online)
A review committee was formed under the J-PARC PAC and a focused review on the Hadron Experimental Facility extension project was held.
Follow the link to get the review report.
HEF extention related presentations
Presentations
Workshops related to the extension project
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"Town meeting 2025 on the Extension Project for the J-PARC Hadron Experimental Facility (J-PARC HEF-ex Town Meeting 2025)"(2025/2/20, Tokai, hybrid.)
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"4th International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility (J-PARC HEF-ex WS)"(2024/2/19-21, Tokai, hybrid)
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"3rd International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility (J-PARC HEF-ex WS)"(2023/3/14-16, Tokai, hybrid)
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"2nd International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility (J-PARC HEF-ex WS)"(2022/2/16-18, online)
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"International Workshop on the Extension Project for the J-PARC Hadron Experimental Facility (J-PARC HEF-ex WS)"(2021/7/7-9, online)
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2nd HIHR/K1.1 WS: "Strangeness in Neutron Stars -- Physics at J-PARC HIHR/K1.1 beam lines"(2021/6/17-19)
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2nd K10 WS: "Workshop on Physics of Omega Baryons at the J-PARC-K10 beam line"(2021/6/7-9, online)
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1st HIHR/K1.1 WS: "ハドロン拡張HIHR/K1.1ワークショップ〜核物理による中性子星内部の解明へ〜"(2021/5/23, online)
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1st K10 WS: "Workshop on Physics at the J-PARC K10 Beam Line"(2021/5/13-14, online)
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"International workshop on the project for
the extended hadron exprimental facilty of J-PARC"
(2018/3/26-28 KEK Tokai Campus)
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"International workshop on physics at the extened hadron experimental
facility of J-PARC"
(2016/3/5-6 KEK Tokai Campus)
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"HUA workshop on the future of the Hadron Hall"
(2011/10/23 KEK Tsukuba Campus)
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研究会「ハドロンホールの拡張によって展開する物理」
(2010/6/6-7 KEK Tsukuba Campus)
Documents related to the extension project
J-PARC Hadron Hall Users' Association(HUA)
