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Title: Phenix.oncs.tn.18.0
file: anc-sys-req-tof.tex
Ancillary Systems Technical Note
E. Desmond
TOF Computer Liaison: Kazuyoshi Kurita
April 6, 1995
The TOF system consists of 1024 elements of scintillator slats with photomultiplier tube readouts. The scintillator slats are arranged into two azimuth sections. These two sections reside in 2 of the 4 sectors in the east arm of the PHENIX outer detector configuration. The TOF detector is mechanically located between the EMCAL and the TEC PC2 detectors. The issues of concern for the ancillary aspects of the TOF system are the high voltage supply, temperature measurement and cooling.
The high voltage supply system will be used to provide power to the photomultiplier tubes of the TOF detector. There will be 2048 photomultiplier tubes in the TOF detector system. These photomultiplier tubes are mounted on the ends of 1024 scintillator slats. There will thus be two phototube channels per scintillator slat. The design from the November 1994 CDR update calls for the scintillator slats to be mounted on two sectors with 768 slats in one and 256 slats in the second sector. These sectors cover 22.5 degrees and 7.5 degrees in the phi angle respectively.
The TOF high voltage system currently being evaluated is a CAEN model A938A high voltage generator. There will be 1024 high voltage supply sources for the 2048 photomultiplier tubes. Each power supply will thus control two photomultiplier tubes. The high voltage supply will provide up to 1800 Kv at up to 2 ma per phototube.
The control interface to the TOF high voltage generator has not been determined at this time. It is anticipated that should the CAEN system be selected as the source of the high voltage generator then the CAEN V288 VME controller will be similar to the interface which will be available for this system. The V288 VME controller provides an interface between a VME base control system and CAENET based instrumentation.
The PHENIX control system will provide individual control of each high voltage supply unit. For TOF the lowest level of photomultiplier tube control will thus be in units of two tubes. Each of the detector sectors will be able to be controlled and operated independently. The individual power supply units will be able to be enabled and disabled before or during run time.
The output voltage and current will be continuously monitored. It is estimated that the monitor rate will be approximately 1/2 hertz. Display clients will be notified of significant changes in the output voltage. The definition of a significant change will be individually settable for each control unit. Each high voltage supply will have separate warning and severe alarm limits. All alarm conditions will be logged. Each log entry will contain the name of the high voltage channel, the value at which the alarm occurred and the time of the alarm. The occurrence of a severe alarm will cause the automatic shutdown of the alarming high voltage channel. The limit values for the warning alarm and severe alarm condition remain to be specified The alarm response time requirements have not been determined at this time.
The temperature will be required to be monitored in each of the sectors housing the photomultiplier tube arrays. It is estimated that approximately 50 channels of temperature measurement will be required. The complete specification of the temperature monitoring will include the following requirements
turn off HV supply
A number of blower or cooling fans may be required to be controlled to maintain the desired temperature of the photomultiplier sectors. An estimate has been made at this time that approximately 10 cooling control units will be required. The type of cooling control has not yet been determined.
Operator display screens will be developed to display the status of all monitored devices in the TOF detector subsystem. Operator screens will also be provided for individual control of the separately controllable elements of the detector system. The display screens will be viewable from any X Window capable display terminal. The display screens will consist of indicator icons to graphically present the fault status of a monitored detector element. Where values are appropriate, the display screen will consist of text fields or bar or chart graphs.
The present plan calls for a test beam run in 1995 at Tsukuba in Japan. The WBS for the TOF system shows the assembly and test of the TOF detector to begin in the third quarter of 1997. Specific plans for the integration and control of the TOF system for testing will be developed jointly with the PHENIX ONCS group, the TOF detector group and PHENIX integration management.
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