Difference between revisions of "RF Signals Shift"

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== Compton Calorimeter ==
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== RF Master Oscillator Signal  ==
  
The compton calorimeter (CompCal) is an array of 12x12 PWO modules. Light from each module is detected using Hamamatsu R4125 photomultiplier tube,  
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The CEBAF accelerator is controlled by a Master Oscillator Clock running at 1497 MHz,  corresponding to 499 MHz (2.004 ns spacing) per hall with 3-hall operation. The precise 499 MHz RF clock is delivered to the tagger and to Hall D to be used for accurate timing of beam bunches arriving to the experimental area. As part of 4-hall operation, the beam is almost always delivered to Hall D at 249.5 MHz with arrival times synchronized to the RF signal provided by accelerator. This clock is too fast for our detector electronics, so we pre-scale the signal by a factor of 128 as input to our electronics 256.51 MHz. The timing of the leading edge of the clock is aligned with the 499 MHz RF signal, but the phase is arbitrary and must be calibrated.  
which is operated at the typical HV of 800 V.
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== Routine operation ==
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=== RF Initialization ===
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[[Image:GlueX MO Control GUI.png | thumb | 400px | Fig. 1. EPICS GUI that controls the pre-scale factors used to create submultiple clocks from the RF master oscillator signal.]]
  
The shift workers will need to monitor the CompCal performance using the CSS monitoring GUIs described below. The following parameters have to be
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The nominal pre-scale factor for the RF signal is 128=16x8, where the two factors correspond to two electronic stages, which are settable with the RF EPICS GUI shown in Fig. 1. Shift personnel should not need to change this, but if the IOC that controls the pre-scale boards is rebooted, these values may need to be restored to values shown in the figure.  
checked during  routine operation of the CompCal detector: temperature, high voltages, and occupancy plots. If requested by the system expert, the
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shift crew can turn ON and OFF all the HV using the HV GUI.
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The HV voltage parameters, such as  voltage  settings, trip currents cannot be changed by the shift workers.
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=== RF EPICS GUI Screens ===
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[[Image:GlueX MO Control GUI.png | thumb | 400px | Fig. 1. EPICS GUI that controls the pre-scale factors used to create submultiple clocks from the RF master oscillator signal.]]
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== Expert personnel ==
 
== Expert personnel ==

Revision as of 16:25, 20 September 2018

RF Master Oscillator Signal

The CEBAF accelerator is controlled by a Master Oscillator Clock running at 1497 MHz, corresponding to 499 MHz (2.004 ns spacing) per hall with 3-hall operation. The precise 499 MHz RF clock is delivered to the tagger and to Hall D to be used for accurate timing of beam bunches arriving to the experimental area. As part of 4-hall operation, the beam is almost always delivered to Hall D at 249.5 MHz with arrival times synchronized to the RF signal provided by accelerator. This clock is too fast for our detector electronics, so we pre-scale the signal by a factor of 128 as input to our electronics 256.51 MHz. The timing of the leading edge of the clock is aligned with the 499 MHz RF signal, but the phase is arbitrary and must be calibrated.

RF Initialization

Fig. 1. EPICS GUI that controls the pre-scale factors used to create submultiple clocks from the RF master oscillator signal.

The nominal pre-scale factor for the RF signal is 128=16x8, where the two factors correspond to two electronic stages, which are settable with the RF EPICS GUI shown in Fig. 1. Shift personnel should not need to change this, but if the IOC that controls the pre-scale boards is rebooted, these values may need to be restored to values shown in the figure.

Expert personnel

The individuals responsible for checking that the RF is ready to take data and setting its operating parameters are shown in following table. Problems with normal operation of the RF signal 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 RF System
Name Number Date of qualification
Fernando Barbosa (hardware) JLab: 7433 Sep 20, 2018
Axxxxx JLab: 5553 Sep 20, 2018