The J-PARC Hadron Facility is designed as a multipurpose experimental facility for a wide range of particle and nuclear physics programs, aiming to provide the world highest intensity secondary ...beams. Currently three secondary beam lines; K1.8, K1.8BR and KL together with the test beam line named K1.1BR come into operation. Various experimental programs are proposed at each beam line and some of them have been performed so far. As the first experiment at the J-PARC Hadron Facility, the Theta super(+) pentaquark was searched for via the pion-induced hadronic reaction in the autumn of 2010. Also experimental programs to search for new hadronic states such as K-pp have started to perform a physics run. The current status and near future programs are introduced.
An experiment to measure an invariant mass of <inline-formula> <tex-math notation="LaTeX">\phi </tex-math></inline-formula> mesons in nuclear medium is planned as the J-PARC E16 experiment. A trigger ...merging module (TRG-MRG) has been developed to detect leading-edges from 256 channels of discriminator-output signals and transmit those serialized hit data to trigger decision module with four optical links. The result of the test shows enough performance of the TRG-MRG as 1-ns time-to-digital converter (TDC) and data multiplexer with four 6.25 Gb/s transceivers.
A high statistics ∑p scattering experiment has been performed at the K1.8 beamline in the J-PARC Hadron Experimental Facility. Data for momentum-tagged ∑− beam running in a liquid hydrogen target ...were accumulated by detecting the π−p→K+∑− reaction with a high intensity π− beam of 20 M/spill. The number of the Σ− beam was about 1.7 × 107 in total. The ∑−ρ elastic scattering and the ∑−p → Λn inelastic scattering events were successfully observed with about 100 times larger statistics than that in past experiments.
After the radioactive material leak accident at the J-PARC hadron experimental facility on May 23, 2013, we designed a new production target, which is capable of a primary proton beam with the energy ...of 30 GeV and power of 50 kW. It is made of gold and cooled by water through a copper block. For the countermeasures of the recurrence of the accident, the target is enclosed by an airtight chamber and helium gas is circulated to monitor the target soundness. In this paper, technical details of the new target design are presented.
The heavy quark baryon spectroscopy is a key way to understand what the building block of hadrons is. The diquark correlation which is expectedly an essential degree of freedom to describe the hadron ...structure can be investigated from the spectroscopy of charmed baryons. An experiment to observe and investigate the charmed baryons was proposed at the J-PARC high- momentum beam line. The missing mass spectroscopy experiment via the π− p → Y*+c D*− reaction at 20 GeV/c will be performed for the systematic measurement of the excitation energy, the production rates and the decay products of charmed baryons. In addition, the properties of the strange baryons can also be measured systematically by using the same experimental setup. From the systematic study of both charmed baryons and hyperons, the diquark correlation can be revealed which is expectedly an essential degree of freedom to describe the hadron structure.
This paper reports developments of indirectly cooled radiation-resistant magnet coils, which can be loaded with 2000-A dc. This current capacity is required for the most upstream magnets of a new ...high-momentum beam line to be constructed in the future extension of the J-PARC hadron experimental facility. Indirectly cooled coils using solid-conductor-type mineral insulation cables (MICs) and stainless-steel water pipes were adopted to achieve high radiation hardness. MICs were sandwiched by independent cooling water pipes and stacked in a casing, and the entire coil assembly was filled with solder. However, the maximum load applied to the indirectly cooled MIC coils was limited to 1000-A dc, mainly owing to a heat problem at the end parts of the coils. In pursuit of the required current capability, we have carried out load tests using a test sample of the end parts, which consists of MIC current leads and a copper bus bar connecting the MIC conductors, instead of a whole MIC coil. By improving the structure of the end parts, we have succeeded to operate the test piece stably with 2000-A dc in a vacuum.
PDF
