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Main
ArCO2 P 10 CF4 H2
Start of LH2-Target
S0
September 2003
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Additionally to the LH2 S0 target, two new cryogenic targets can be used for proton induced reactions at the FRS. They have been manufactured by CEA/Saclay (France). The first target, for use at S4, is a copy of the already existing target at the entrance of the FRS: 10 mm long and 30 mm in diameter, delimited by titanium foils with a thickness of 15µm each. The second target, for use at S2, has a length of 200mm and 60 mm in diameter and is made of Mylar with a thickness of 125µm. Hydrogen is cooled and liquefied in a two stage refrigeration system. This configuration limits the liquid volume to 20 ml for S4 target and 740 ml for S2 target. The target and the refrigeration system are in a residual 54 litre vacuum chamber at S4, respectively 85 litres at S2 and remain at the FRS The upper part of the target system with the cold head, turbo molecular pump, valve, vacuum gauge and the actuator cold valve will be in a joint use for all new cryogenic targets at GSI. This concerns also the cryogenic rack with the storage tanks for Hydrogen and Deuterium, the Helium compressor and the electronic racks. The safety of the whole system is in according to the Fermi lab regulations „Storage and use of flammable gases at physics experiments“ and is classified as risk class 0, that means hydrogen volume Ł 6.5 m3. The basic idea behind safe handling of any flammable or explosive gas is to eliminate oxygen and to prevent exposure to any energy source that could cause ignition. The following general guidelines are used for the design of the gas handling system: · No valves which could open the system to air · Each pressure monitor is spark proof · The pump used in the storage tank circuitry is leak proof (hermetic) · The only other electrical equipments in direct contact with hydrogen are liquid level sensors.
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