Minutes of 49th FFIR/BDSIM meeting on 3/19/2003

The meeting was held in a room of 425 at KEK, 10:00-11:30, 3/19/2003. We discussed on beam dump, FEATHER, and others.

(1) Beam dump (S. Ban, KEK)

(transparencies, 4 pages, pdf ,120KB ) Ban briefly explained a water cooling system in the JLC beam dump which has been studied and reported by Hitachi Engineering Co. and Hitachi High Technologies Co. . Since the study is based on company's experiences of atomic nuclear plants and it is also very preliminary, quoted results should not be taken seriously. @The results are rather considered to be a starting point for the realistic system.

The water cooling system consists of three closed loops assuming the total heat quantity of 12MW. The first loop includes the beam dump itself, a water purifier and a tank for water storage during maintenances. Inlet and Outlet water temperatures are 80 and 50 deg. C, respectively, at a first heat exchanger. A water-purifier system is connected to the first loop in order to filter radioactive ingredients. The first loop system must be located in very restricted area in terms of radiation safety. Necessary space was estimated to be 15 x 20 x 3(H) m3. At the second loop, the water temperature will be cooled down from 65 to 40 deg.C . The second loop system includes also a recombination system of generated hydrogen and Oxygen gases. The second system may also occupy a volume of 15 x 20 x 3(H) m3. The third loop system has a cooling tower on the ground surface, where inlet and outlet water temperatures are 50 and 30 deg.C .

He also showed calculations of radiation dose in ground (soil) by MARS, where the beam dump is a water tank of 1.6m diameter and 10m length and it is set inside of soil. The beam energy and power are 250GeV and 10MW, respectively. Soil of 10m thick is so effective in terms of radiation shield that the dose is estimated to be less than 1 micro-Sv/year. For an example, the KEK tolerance is 50 micro-Sv/year while the regulation value is 100 micro-Sv/year. Therefore, the radiation dose must be negligibly small on the ground surface. However, a radiation dose with soil of 5m thick is far beyond these tolerances, which is estimated to 105 micro-Sv/year. So, there is a very restrictive area around the beam dump as expected.

(2) Fast feedback system "FEATHER"(N.Delerue, KEK)

(transparencies, 7 pages, pdf ,3.5MB ) First, Nicolas briefly introduced what he has seen at the nano-BPM workshop, March 11~12. Especially, he had very useful discussions on the stripline and button BPM, MATLAB simulation with the FONT/UK/SLAC people. At the latest beam test, he succeeded to observe a beam-deflection by the kicker with help of Mark Ross and Hayano for reduction of dispersion. The beam displacement was observed to be about 200 micro-m at the end of the extraction line. He demonstrated animations of the simple and delayed models by using MATLAB. He also showed equipotential lines of the kicker for calculation of impedance by POISSON. Finally, he introduced the FEATHER home page of http://acfahep.kek.jp/subg/ir/feather , where archives of previous talks, monthly reports, proposals etc. can be found.

The next meeting will be on 9 April (Wed.), 2003,13:30 - 15:30 am at 3 gokan, 425 .