Cryogenic Target Shift

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The Cryogenic Target

The Hall D cryogenic target consists of a tapered kapton target cell of 29.9 cm length, 2 cm diameter, a vacuum chamber, a pulse tube refrigerator, a compressor and its water cooling system, a gas manifold and panel, the electronic controls (PLC logic), a support cart and safety storage tanks. The figure below shows some of its main components.

Target fig.png

The cell can be filled with liquid H2 (physics run) or gas H2 (empty run). It has a 130 um kapton wall and 75 um entrance and exit kapton windows.

When filled with LH2, the operating pressure and temperature are P=18 psia and T=17K.

Routine Operation

There are 3 routine operations:

  • Empty target. Refrigerator is turned on and cell is cooled to temperature for cold H2 gas.
  • Fill target with LH2. Refrigerator is turned on and cell is cooled to temperature for liquid H2.
  • Turn off. Turns off refrigerator and lets the target warm up.

To turn on the target, use Empty or Fill buttons. It takes about 6h to cool the target from room temperature. To turn the target off use Turn off button.

Operation manual for the target can be found here.


Safety interlocks protect the target if the temperature decreases below 16K or the pressure decreases 16 psia.

If such event happens or if the target warms up, the target should not be damaged. However, beam time will be lost. Call an expert immediately

In case of problem with remotely controlling the target

If the target control freezes, there are several ways to restore them, described here.

Expert personnel

The individuals responsible for checking that the cryogenic target is ready to take data and setting its operating parameters are shown in following table. Hall D contacts should be called first Problems with normal operation of the cryogenic target should be referred to those individuals and any changes to their settings must be approved by them. Additional experts may be trained by the system owner and their name and date added to this table.

Table: Expert personnel for the Cryogenic Target
Name Extension Date of qualification
Alexandre Deur Office: 757-269-7526 / Cell: 757-871-5931 June 12, 2014
Chris Keith (Target group leader) Office: 757-269-5878 / Cell 757-746-9277 June 12, 2014
James Brock (Target group) Office: 757-269-7860 / Cell 757-871-5374 June 12, 2014
Chris Carlin (For computer control issues) Office: 757-269-5971 / Cell 757-559-1269 June 12, 2014