-- EstherBabetteMenz - 2021-04-25

Manual for Particle Detector Drives at the CRYRING@ESR electron cooler

There are currently two particle detector setups in operation downstream of the CRYRING@ESR ElectronCooler. Both are used to detect downcharged product ions from the interaction between the ion and electron beams inside the cooler. The YAP:Ce scintillation detector (YR03DS1HA) sits directly behind the first dipole magnet after the cooler and is used for light ions in low charge states (including neutral reaction products). The CEM detector (YR04DS2HA) is located further down the straight section (YR04) and is used for heavier, highly charged ions (up to and including He-like uranium). Both detectors are used in recombination experiments at the electron cooler, including dielectronic recombination measurements.

Overview

• The detector setups have two drives: a slow step motor drive for positioning and a fast pneumatic drive for rapid retraction of the detector head during beam injection.
• The step motor drive is controlled via “DeviceControl” and has a range of 40 cm. It has to be in the outside position before the valve connecting the detector chamber with the ring can be closed.
• The pneumatic drive has a range of 5 cm and is controlled via a panel in the “Messhütte”. In automatic mode the detector is retracted with every beam injection. In manual mode in can be moved from the panel.
• The vacuum conditions in the detector chamber should be monitored closely while the pneumatic drive is on automatic. The relevant data can be found here (green line).

Emergency Instructions

Using the pneumatic drive in automatic mode during experiments puts stress on the vacuum bellows which might lead to vacuum leaks. Information about the vacuum read-out can be found here.

In case of a (suspected) vacuum leak, please proceed as follows (March 2024):

1. Stop the pneumatic drive by pulling the timing cable (see below) that provides the drive gate in the electronics hut (see picture on the right for location).
2. Move the detector to position "290 mm" with the step motor drive. You should now be able to see the detector head if you uncover the window on the left-hand side of the detector chamber.
3. Ask the main control room to open the cave and close the valve between the ring vacuum and the detector chamber (see CRYDetVacuum).
4. Shut down HV supply of the detector (optional).

Important: Make sure step 2 is completed before attempting step 3! Closing the valve before the detector arm is fully retracted will lead to substantial damage and further vacuum leaks!

Version of the protocoll for normal operation of the pneumatic drive:

1. Stop pneumatic drive (i.e. switch from "automatic" to "manual", see below for instruction).
2. Make sure the pneumatic drive is in the inside position, if not, move it there by pressing inside in manual mode.
3. Move detector to the outside position of the step motor drive (not the pneumatic drive).
4. Ask the main control room to open the cave and close the valve between the ring vacuum and the detector chamber (see CRYDetVacuum).
5. Shut down HV supply of the detector (optional).

Pneumatic Drive

March 2024: Due to a poorly understood problem with the pneumatic drive control the normal solution (outlined below) is not available at the moment. Instead, an improvised solution has been set up which makes it possible to run the drive in automatic mode. Please see the emergency instructions above for details on how to stop the pneumatic drive.

There are two drive modes for the pneumatic drive:

• in "manual mode" the detector can be moved between the outside and inside positions using the touch panel,
• in "automatic mode" the detector receives drive signals as part of the ring cycle and is moved to the outside position before beam injection and then back into place for the measurement.

The pneumatic drive is currently controlled from a touch panel in the electronics hut (next to the "Messhütte" on the CRYRING roof). Network access to the controls is planned but not yet implemented.

Switching Drive Modes

1. Press "Manual" on the bottom of the screen.
2. If prompted for a password, type it in, press enter and confirm with "ok". The password will be provided to shift crews.
3. Press "Manual" again.
4. The status in the top right corner should change from "Automatic" to "Manual".

The change from "Manual" to "Automatic" is equivalent, however you might have to wait for the next ring cycle before the actuator status is updated.

Stepper Motor Drive

The step motor drives are controlled via DeviceControl which is a control system app that can be openend from the App Launcher (CRYRING tab). After selecting the appropriate context DeviceControl will display a wide variety of different drives (e.g. Faraday cups, scintillation screens, etc.). The particle detectors are labelled "YR031" (scintillation detector YR03DS1HA) and "YR042" (CEM detector YR04DS2HA - currently not in operation). Clicking the drive symbol (see picture below) will open a widget that allows you to change the detector position.

The most important function in case of a vacuum emergency is driving to the outside limit:

• Set "outer limit" as goal.
• Click "Drive" in order to initiate the drive.
• Check "actual position" to see whether the detector is moving.
• Make sure the outer limit has been reached, especially before closing the valve (a sub-millimetre difference between the set and actual position is not a problem).

To drive to an arbitrary position:

• Set value and confirm with "Accept".
• Click "Drive" in order to initiate the drive.
• Check "actual position" to see whether the detector is moving.

If the motor status in the drive widget reads "Interlock" the valve connecting the detector chamber with ring vacuum is closed (or not fully openend). The interlock blocks the step motor drive in order to prevent damage to the detector and the vacuum system.