Collimator Cave

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  This is where the photon beam first enters Hall D. The tagger hall is 17 meters upstream.

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  This is the apparatus that will hold the active collimator.

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  A pic of me next to the future home of the active collimator. Photo credit to Sascha.

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  You can see the collimating hole through which the photon beam will travel in this pic; it is 3.4 mm in diameter, and is comprised of a 30 cm long tungsten block. There is also a 5 mm diameter hole (to the left).

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  The backside of the collimator in the previous pic.

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  A 0.8 T permanent magnet which is used to sweep away the various particles (positrons, electrons, compton, showers, etc) from the result of collimation.

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  A downstream shot of the collimator cave. That's Sascha on the right.

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  A vacuum chamber. The particles that form as a result of the collimation will be steered into a lead block that will be installed below it.

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  A second collimator to eliminate the secondary photon "halo" around the photon beam. The halo is a result of primary collmation.

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  A second magnet.

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  This is where the collimated beam will exit the second, less powerful permanent magnet.

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  An upstream view of the "Collimator Cave."

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  The collimated beam will travel through this opening to the main room of Hall D, where the Barrel Calorimeter (BCAL) and Forward Calorimeter (FCAL) are located.