| Table of Contents |
|---|
Introduction
The Decarad system was developed at JLab - it consists of 10 radiation detecting heads (geiger-mueller (GM) tubes) that connect (signal & HV cables) to a central box. That box has a board inside for changing the HV level and reading out the GM tube signals. The center box is connected to a digi port server via DB9 at box to RJ50 at the digi, which is then connected to the outside world via ethernet. The software uses the epics tool Stream with an asyn connection to the digi to send commands to the center box to read and write. The software is part of the RadiationMonitoring slac epics package.
The plan for commissioning is to attach the 10 heads to a frame on wheels (made from 80/20) and put the digi and central unit on a cart and roll the system next to the CM under test. In the navigation bar to the right, under the decarad heading is a link to the page with the diagrams showing the nearest ethernet, 120V, and 208V outlets to each CM.
Photo of 1 center box plus one radiation monitor with ruler
Help for Users
From the lower left corner of lcls home SC gun - X-ray/MISC+Global - select Decarad 1 or Decarad 2 to get the pydm display. It shows the read backs of the high voltage, the firmware number, a heartbeat, and the individual channel radiation read backs in approximate mr/hr. The GM tubes saturate with high radiation:
Screen shot of saturation curve from LND 714 datasheet - attached below.
Also on the pydm display is a place to type in the location of the system ("near CM35" for example) as well as positions for the individual heads ("near cavity 1", "between cavitiies 7 & 8", for example). These typed in values as well as the desired high voltage setting is saved across IOC reboots. All numeric values except for the heartbeat and firmware number are archived.
The radiation read back PV names are RADM:SYS0:x00:GAMMA_DOSE_RATE, where x is 1 or 2.
About the software (used to be "For Naming Czars")
...
We have two decarad systems. Each consists of 10 small Geiger-Mueller (GM) radiation detecting heads that are connected (signal & high voltage (HV)) to a central unit which has some brains to control the HV level and read out the measured dose rates. The plan is to mount these to two frames that will be positioned near cryomodules during RF commissioning to measure radiation. The systems will be moved every day or two as we commission all cavities. The systems were designed and built at JLab and used for many years. The decarads are talked to through a DB9 connector connected to a Digi Portserver. The software uses EPICS ASYN and Stream Device to send the commands to set the HV, read back the measurements, etc. The software is part of the RadiationMonitoring slac epics package. The proposed software is currently in afs:
...
There are two sets of decarads (10 heads + central unit) so the PVs listed above are doubled and differentiated by $(P).
Suggested $(P) = RADM:SYS0:100 or RADM:SYS0:200 for the two systems.
Photo of 1 center box plus one radiation monitor with ruler
< End section for Naming Czars - thank you for your help! >
To Do:
- Order from
TECO - 80/20
L-Com - DB9 connector parts
(recv'd) Amazon - extension cord, enet cables, reels
(recv'd) McMaster-Carr - carts, velcro zip-ties
(Thank you Bernadette!) - PV names approved - finish pushing through tweaks (displays, archive, casr, dbs)
- Get db9 cables from Doug
- Test digis in tunnel
- if cables ok, roll up other cable on reel
- If not, get more cables
- Test a system in the tunnel
- Release EPICS software, start softioc
- See what values HVSTAT gets
- Release display, add button to another display to open it
- Test software: displays, save/restore, archiving
- Get parts from Mike's office
- Cable tags on cables
- Ask Charlie to configure Digis
- Build Put caps on frames
- Make DB9/RJ50 cablesAssemble carts and extension cords and enet cables on reels
- Test velcro around GM tubes
Introduction
...
Cable Connection
Notes on cable connection (from email 8/12/21)
...