Investigations of energy penetration for the 2003 design of the target cell at the Hermes experiment

Calculations have been made to investigate the energy penetration through the pumping holes of the beam tube at the interaction point of the HERMES experiment at HERA. A shielding screen made from etched nickel foil, pressed into the aluminium of the target cell, was proposed. Several different models were studied. Calculations for the new design of the spring fingers were also made, and the results for the 2000 design are included for comparison. As there have been no measurements as yet, the 2000 values are the only indication of an upper limit of radio frequency interference which is not tolerable for the detector electronics. The effect of discretisation on the results was also analysed.