Accident scenarios on a quadin MTA beam line

Igor Rakhno

April 20, 2007

The scenarios

• Beam hits the beam pipe center inside the quad – model 1

• Beam hits the quad pole – model 2

• The quad is ~ 17 m upstream of the concrete shield block

• Vertical angle = 50 mrad

• 400 MeV protons

• Normalization does not matter because we are looking for a relative behavior. Here it is 2×1014 p/s.

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• Calculated distributions atop the berm are poor.

• More or less reliable data were obtained for a 1-ft layer inside the berm, 5.3 ft above the concrete ceiling. In other words, vertical distance between the layer and the beamline is 405 cm.

• Atop the berm mostly low-energy neutrons and gammas exist, almost no stars.

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Plan view of the Linac – MTA area

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Linac – MTA area: fragment with a quad

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Quad cross section

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Star density inside soil, 5.3 ft above the concrete ceiling

Model 1 Model 2

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Neutron flux inside soil, 5.3 ft above the concrete ceiling

Model 1 Model 2

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Star density and neutron flux vs distance from the quad

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