J-PARC Project Newsletter

               _______ January 23, 2007_______

     Japan Proton Accelerator Research Complex under construction jointly
      by the Japan Atomic Energy Agency (JAEA) and
      the High Energy Accelerator Research Organization (KEK)


Dear Friends,


We are very pleased to inform you that at 0:54 am on January 24th 

in Japanese time the J-PARC linac accelerated the H-minus beam

up to the energy of 181 MeV, which is the design value, and it will 

be used for the injection to the J-PARC Rapid-Cycling Synchrotron

 (RCS). The beam energy was measured by means of time-of-flight.

The peak current, the beam pulse length, and the repetition rate were

5 mA, 20 micro s and 2.5 Hz, respectively. These values were selected 

for the purpose of the initial beam study, to avoid a possible damage 

in accelerator components, if something wrong happened at a high beam 



The J-PARC linac was ready for the acceleration up to 181 MeV at midnight

last Friday. Afterwards, an amplitude/phase scan for each pair of the 

separated drift-tube linacs has been tried by using one klystron and, 

finally, the scan through fifteen pairs were completed this week.  

In each scan  the beam energy was measured by the time-of-flight 



During the beam commissioning, both RF power source and cavity 

system have been very stable. This stability together with a very 

accurate alignment of all the magnets, especially in the drift-tube linac,

were the two major elements to allow a rapid tuning of the linac.


We would like to thank all of you who have been supporting us. 

The above result could be accomplished only by the help and the 

contribution of all of you. On behalf of the J-PARC accelerator team, 

we would like to express our sincere appreciation. In particular, 

all workers, technicians, and engineers from industries, who have been 

involved in manufacturing, construction and commissioning of the 

J-PARC linac, are highly appreciated. 


Thank you again,


Yoshishige Yamazaki

Division Leader, Accelerator Division, J-PARC Center