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Guide taper

The wavelength averaged loss in the 30cm monochromator guide cut is 5.6%, so the total flux at the beginning of the taper is 4.2 x 108 n/cm2/s . At the end of the taper we have a flux of 2.11 x 109 n/cm2/s and a cross section that has been reduced by 30%. Thus 1.13 x 1010 n/s are deposited over the 2.155 m length of the taper, a line source of 5.24 x 107 n/cm/s. Merely using 5 inches of iron reduces the radiation below the design goals. However, a significant component of the gamma dose is due to the core gammarays scattering from the taper. A memo discussing this contribution to the dose and the shielding thereby required is in preparation.