J-PARC Project Newsletter Special issue

            30 May 2008


Birth of Pulsed Neutrons in J-PARC

We are very pleased to inform you that we have recorded a memorial
event of the first neutron production at J-PARC Materials & Life Science
Experimental Facility (MLF) on May 30th, 2008. At 14:25, a shot of 3GeV
protons from RCS (3 GeV synchrotron) was injected to the mercury
target at MLF.  Pulsed neutron beam extracted from the de-coupled
moderator was detected by Li-glass detectors which were incorporated
in the Current type Time-Of-Flight (CTOF) technique placed in the beam
line of NOBORU (an instrument for neutron source characterization).
The first memorial neutron energy spectral intensity derived from the
CTOF data is shown in the photograph, which is displayed in
http://j-parc.jp/MatLife/1stBeam/PromptReport.JPG .  Also, please
find there, the incident proton beam profile recorded. Right after the
neutron production event, beams were introduced to four instruments
consecutively to test the system performance.

It was a very quiet but exciting achievement of important J-PARC
landmarks. The spectrum displayed on the monitor screen confirmed
our achievement for 7 years challenge. Although the power of accelerator
was still low as equivalent to only 4 kW, it was a calm and convincing
departure to the J-PARC MW pulsed neutron source. All endeavor
done by the MLF neutron team of JAEA and KEK, was rewarded by
this historical moment.

In coming September, the first muon beam production is scheduled.
By the end of October, 2008, more dedicated tests of the instruments
are to be performed with more intense proton beam power. The first
user experiment is planned to start from December, 15, 2008. To meet
this schedule, the first call for proposal will be announced in July 7, 

              J-PARC Center MLF Division Director Yujiro Ikeda