I )   Dissembly of cryostat CCD head

1. Removal of CCD detector, if this does not affect the adjustment
2. Dissembly of the cryostat head:
   • No dissembly of the inner so-called UFO part which holds the adjustment via the fiberglass epoxy parts, if the adjustment is already done.
   • If there is no prior adjustment, dissembly of all parts.
   • Sorting of all the parts according to its material.

II )   Cleaning of the cryostat components

1. Read the instructions given in the webpage   Ultraclean CCD project   under the caption   Needed equipment and precautions.
2. Read the instructions in the same webpage under the caption   Handling procedures and working conditions.
3. Read the treatment instructions under the caption   Treatment of cryostat components. This is giving the washing methods and the baking temperatures of the different materials.
4. All components have to be first cleaned by hand with paper and acetone respectively alcohol.
5. The materials which are suitable to be washed in an ultrasonic bath are carefully introduced into this bath. The bath has to at least 2/3 filled, otherwise the device is damaged. The parts has to be handled with care in order not to scratch the surfaces, especially the sealing surfaces.
6. The ventilation of the fume cupboard has to be run.
7. Do not use acetone or alcohol in the ultrasonic bath because it is a fire hazard! Use a special detergent (TICKOPUR) instead.
8. The parts have to be cleaned two times in the ultrasonic bath. The second time in pure very clean water! The first bath should not contain dirty solvents or solvents, which have been used more than 3 times.
9. Use hand gloves, eye goggles and a gasmask when handling the parts from and to the ultrasonic bath.
10. Let the parts dry in the air before going to the oven.
11. If a part is not yet clean, repeat the procedures.

III )   Baking of the cleaned parts

1. Read the oven manuals and clean the oven with scouring powder and water first and then with alcohol.
2. Pre-heat the oven to the desired temperature before filling it.
3. Wear eye goggles and leather gloves, when working with the hot ovens.
4. Put in the corresponding parts to the correct ovens. Parts in the wrong ovens with too high temperatures can be destroyed! Watch the oven temperature. We use the installed digital thermometer and additional liquid thermometer which are vacuum oven proof.
5. Wait until the parts have reached temperature and then start the vacuum pumping of the oven.
6. Let the parts as long as possible in the ovens, at least the specified times in the handling/treatment instructions.
7. At the end let the oven cool down, carefully let in air and remove the parts with cleanroom gloves.

IV )   Storage of clean parts

1. All cleaned parts have to be stored in a clean ambient inside of a box or a laminar air-flow bench.
2. Don't touch the parts with the fingers.

V )   Reassembly of the cryostat head

1. This is done in a laminar air-flow bench and with clean-room gloves, only the CCD detector or parts very near to this detector are touched with the fingers in order not to handle these delicate parts with too high risk.
2. In principle the reassembly is done in the reverse order as the assembly.
3. Let the cryostat head in the clean air bench, or assemble it as soon as possible to its nitrogen tank in order to avoid dust inside.
4. Also use an antistatic arm connection, if static sensitive parts (CCDs or electronic) is handled.
5. During the whole assembly antistatic air is used to avoid dust inside the cryostat.

Back to   "Ultraclean CCD project"

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Send comments to   <odt@eso.org> Last update: Mar 24, 2004 Written by   Sebastian Deiries, webdesign by   EVI