[Halld-tagger] Fwd: 4-Hall Service Catch-All Module. 2 week open request period. (fwd)

[Eugene Chudakov]

There is a plan to build a new SCAM module (one which sets the beam
structure for the CW, tune and other beam types). They are collecting
comments/wishes from the halls. If one thinks that we would need
additional features - please let us know.

Eugene

---------- Forwarded message ----------
Date: Wed, 1 Apr 2015 17:33:31 -0400 (EDT)
From: Hari Areti <areti at jlab.org>
To: Cynthia Keppel <keppel at jlab.org>, Volker Burkert <burkert at jlab.org>,
     Steve Wood <saw at jlab.org>, Eugene Chudakov <gen at jlab.org>
Cc: Rolf Ent <ent at jlab.org>, Patrizia Rossi <rossi at jlab.org>
Subject: Fwd: 4-Hall Service Catch-All Module.  2 week open request period.


Dear Hall Leaders,
I am forwarding a message from John Hansknecht, an engineer with the injector group. If you want additional features to
the SCAM module than the one John has described below, please respond to him (or me) with your requests. John asks
that you respond withing 2 weeks after which time, he may not be able to accommodate your input.

Thank you.

-H

From: "John Hansknecht" <hansknec at jlab.org>
To: "REU2013 Students" <areti at jlab.org>, "Mike Spata" <spata at jlab.org>, "Daniel Sexton" <dsexton at jlab.org>, "Henry Robertson" <robertsn at jlab.org>, "Matt Poelker" <poelker at jlab.org>, "Joe Grames" <grames at jlab.org>, "Riad Suleiman" <suleiman at jlab.org>, "Marcy Stutzman" <marcy at jlab.org>, "Arne Freyberger" <freyberg at jlab.org>, "Pamela Kjeldsen" <kjeldsen at jlab.org>, "Scott Higgins" <higgins at jlab.org>, "roger flood" <flood at jlab.org>, "garza" <garza at jlab.org>, "Peter Anthony Francis" <francis at jlab.org>
Sent: Wednesday, April 1, 2015 11:51:24 AM
Subject: 4-Hall Service Catch-All Module. 2 week open request period.

All,

The Service Catch-All Module (SCAM) that creates the beam timing modes has been in operation for 16 years. Some of you have requested new timing features in the past, but were denied due to limited code space in the existing module. We have not kept a formal record of those requests.

A new "Four Hall SCAM" is being designed to replace the existing three hall system. It is scheduled for implementation in the summer of 2016 when a fourth laser is added to the laser table to support simultaneous four hall operation. The new SCAM module will have the same beam timing capabilities as the existing module. For 2 weeks, we are accepting requests for new features that may be desired. After this period we would prefer to lock down the new requirements document.

Please know that the fundamental capabilities of the tune mode system will not change. The beam will have a rise and fall time of 250ns between full transmission and minimum transmission. The "beam" and "mod" modes will be combined, and there is no provision for variable modulation depth as some of you may remember from the thermionic gun days. The beam timing will remain locked to the 60hz zero crossing, and will have a provision to allow a free-running 59.5hz clock that will make observations of line induced beam motions evident.

Recall the following timing features are presently available:

1. Viewer limited mode: Beam is mostly off, and pulsed on every 16.7ms for 1 to 10 us. This "on" period is adjustable by EPICS in 1us steps.

2. Tune mode: Beam is mostly off. Every 16.7ms, the beam is pulsed ON for 250us, then OFF for 100us, then ON for 4us.

3. CW mode: Beam on CW with no timing features.

4. User mode: Beam ON and OFF timing pulse structures are completely adjustable within the confines of internal timing register resolution of 250ns.

5. A beam sync to beam delay feature is present on each output to properly sync all beam production some time period away from the line zero crossing so the SEE BPM's can catch the 4us pulse at the proper time

We presently have a "Master FSD" and three individual hall FSD fiber inputs to the module. The individual hall FSD's were never implemented and it appears to be a nightmare scenario to implement a four hall FSD when any laser can be phased to go through any slit to provide beam to any hall. My suggestion is to only accept a master FSD, and then let the operators review the cause and recover beam to the halls that are unaffected, just as they do today. The new board can be designed to accept an add-on board in the future if individual FSD's are somehow implemented.

We presently have an input for master PSS A and B, which will remain. We presently have inputs for PSS A&B individually from each hall that were never utilized. These will be eliminated.

For those that want to read the full capabilities of the existing card, I have attached the original 1998 requirements document written by Hari Areti and some timing notes provided by Roger Flood.

I look forward to any requests during the open request period, which ends April 15th. Every remark or question is important, so don't hesitate to contact me so I can record your request to be discussed at the design review. I'm happy to answer quick questions, but feature requests should be put in writing so they can be tracked.

Thank you,

John
ext 7096
-------------- next part --------------
A non-text attachment was scrubbed...
Name: SCAM Requirements 1998_2.pdf
Type: application/pdf
Size: 60852 bytes
Desc: 
Url : https://mailman.jlab.org/pipermail/halld-tagger/attachments/20150401/18264334/attachment-0002.pdf 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: SCAM Requirements 1998.pdf
Type: application/pdf
Size: 199068 bytes
Desc: 
Url : https://mailman.jlab.org/pipermail/halld-tagger/attachments/20150401/18264334/attachment-0003.pdf 
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: scamreg.txt
Url: https://mailman.jlab.org/pipermail/halld-tagger/attachments/20150401/18264334/attachment-0002.txt 
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: tunemod2.txt
Url: https://mailman.jlab.org/pipermail/halld-tagger/attachments/20150401/18264334/attachment-0003.txt