Author/Authors :
Abe، نويسنده , , R. and Abe، نويسنده , , T. and Aihara، نويسنده , , H. and Asano، نويسنده , , Y. and Aso، نويسنده , , T. and Bakich، نويسنده , , A. and Browder، نويسنده , , T. and Chang، نويسنده , , M.C. and Chao، نويسنده , , Y. and Chen، نويسنده , , K.F. and Chidzik، نويسنده , , S. and Dalseno، نويسنده , , J. and Dowd، نويسنده , , R. and Dragic، نويسنده , , J. and Everton، نويسنده , , C.W. and Fernholz، نويسنده , , R. and Friedl، نويسنده , , M. and Fujii، نويسنده ,
Abstract :
We have upgraded the beampipe and the silicon vertex tracker of the Belle detector for increased luminosity and to achieve better vertex resolution. The radius of the beampipe was reduced from 2 to 1.5 cm to achieve better vertex resolution. In order to reduce the beam background that could accompany the reduction of the beampipe radius, a massive mask made of tantalum and tungsten was placed on each side of the central section. The total weight of them is 40 kg. The maximum radiation dose of the silicon tracker is measured about 80 krad/yr. This is lower than the dose of 100 krad per year with the previous beampipe even though the beampipe radius is smaller. The beampipe is designed to minimize heating, and enough cooling power is provided by the liquid cooling.
