How to set magnetic fields in the GPD spectrometer
- the GOSSEN power supply (manual (PDF, 3.6MB)), (datasheet (PDF, 0.4MB)) recommended for low fields, 0-250G or
- the HELMHOLTZ beam line power supply for high fields, 0-6660G.
The respective power supplies can be set from DELTAT by
- Exp. Magnets... GOSSEN... or
- Exp. Magnets... HELM...
- SET Magnet HELM 150 30
- SET Magnet GOSSEN 150 30
- A 16-bit DAC is used to set the 6.6kG-Helmholtz power supply, i.e. the resolution is about 0.1G. An ADC with only 12-bit resolution
- Like all other magnet power supplies HELMH2 (650A/250V) is located on the second floor above the Studios but it is placed at the end
- Setting HELM to zero causes the Helmholtz power supply to switch
- The GOSSEN can be switched off only manually. The GOSSEN power supply
- There is no auxiliary field available, i.e. the coils have to be rotated for calibration
- Make sure that the vacuum chamber used for the horizontal cryostats (CCR and Chemistry Cryostat) is not inserted.
- Make sure that UP/DOWN detectors are not inserted.
- Locate the latch lock on the spectrometer table on the beam entrance side and unlock it by rotating the latch lock bolt by 180o. In this way the lock bolt is lifted out of the hole in the supporting table of the coils which become now free for rotation into the desired orientation.
- Watch the high-current cables and the cooling water tubes during rotation.
- Use the latch lock to fix the coil orientation.
- Insert the UP/DOWN detectors and the horizontal vacuum chamber if necessary.
Beam bending in TF:
The GPD-stepper-motors are controlled from DELTAT using
Modify Devices... smngpd.... Please read the operating instructions carefully.
Calculator of settings for µ-Momenta 60...110MeV/c and TF < 6.5kG:
Please refer to the PDF-table for a list of spectrometer settings at given magnetic fields and muon momenta as well as for the model functions and parameters. A little program for intermediate values is also available on the desktop of the experiment console (PC6011).
Please note: The motor drives are limitted as follows:
GPD_VERTICAL 0 ... 110mm COLLIMATOR -31 ... +40.5mm DETECTOR -26 ... +30mm
Intensity adjustment by slit FS81: Please leave the vertical slit drives allways at 200 (FS81-O = FS81-U = 200) and adjust intensity by FS81-L and FS81-R only. Please note: Uncontrolled movement of any motor-driven parts of the spectrometer can cause serious damage to the spectrometer and its components! Please check carefully by visual inspection inside the area if all parts you intend to move under remote control from the Studio can move freely. Please, switch off all motor drives not in use on the manual control board in the area.
- The average background in the area is of the order of 0.5 Gauss.
- The remaining field originating from
- The beamline magnets cause a field of 0.1 to 0.2 Gauss in the center of the
- The passage of the crane causes a change of approx. 0.025 Gauss and may
-- Main.AlexAmato - 12 May 2014