[Halld] CEBAF Status: No beam for at least a week and shifts canceled

[Cristiano Fanelli]

Dear GlueX Collaborators,

As discussed today during the RC meeting, the accelerator has recently encountered several problems (see below Arne's email - kindly forwarded by Alexandre - for a detailed explanation of the status).

In light of this, shifts are canceled up to next Friday, 8am.
The next RC meeting will be on Tuesday, September 4, usual time.

Thanks,
—Cristiano, RC





----- Forwarded Message -----
From: "Arne Freyberger" <freyberg at jlab.org<mailto:freyberg at jlab.org>>
To: "Bob McKeown" <bmck at jlab.org<mailto:bmck at jlab.org>>, "Rolf Ent" <ent at jlab.org<mailto:ent at jlab.org>>, "rossi patrizia" <rossi at jlab.org<mailto:rossi at jlab.org>>, "Javier Gomez"
<gomez at jlab.org<mailto:gomez at jlab.org>>, "Mary Logue" <logue at jlab.org<mailto:logue at jlab.org>>, "Bob May" <may at jlab.org<mailto:may at jlab.org>>, "Will Oren" <oren at jlab.org<mailto:oren at jlab.org>>, "Rusty Sprouse"
<sprouse at jlab.org<mailto:sprouse at jlab.org>>, "Michael Maier" <mmaier at jlab.org<mailto:mmaier at jlab.org>>, "Allison Lung" <lung at jlab.org<mailto:lung at jlab.org>>, "Stuart Henderson"
<stuart at jlab.org<mailto:stuart at jlab.org>>, "Lauren Hansen" <lhansen at jlab.org<mailto:lhansen at jlab.org>>, "Mike Spata" <spata at jlab.org<mailto:spata at jlab.org>>, "Andrei Seryi" <seryi at jlab.org<mailto:seryi at jlab.org>>,
"burkert" <burkert at jlab.org<mailto:burkert at jlab.org>>, "Eugene Chudakov" <gen at jlab.org<mailto:gen at jlab.org>>, "Cynthia Keppel" <keppel at jlab.org<mailto:keppel at jlab.org>>
Cc: "Latifa Elouadrhiri" <latifa at jlab.org<mailto:latifa at jlab.org>>, "Dave Mack" <mack at jlab.org<mailto:mack at jlab.org>>, "Alexandre Deur" <deurpam at jlab.org<mailto:deurpam at jlab.org>>, "Steven
Suhring" <Suhring at jlab.org<mailto:Suhring at jlab.org>>
Sent: Friday, August 31, 2018 9:22:20 AM
Subject: CEBAF Status: No beam for at least a week

Not much new information on the source of the North linac vacuum leak.

Yesterday clean rooms were installed on two girders in the North linac
and prepared (made clean) for today's connection to the beamline.
Leak checking will start soon after the connection is made.

In parallel, the five modules (NL21-NL25) of the North linac will be
warmed up over the weekend.   This warm-up is needed to release frozen
gases on the beamline surfaces.  It will also "ready" these modules for
extensive leak checking if the leak is not in the warm section between
the cryomodules.  Best case is that the leak is identified and repaired
in a warm girder early next week (perhaps even today), followed by
cooling down the warmed up modules next week.   This *may* put us in a
position to deliver beam by next Friday.

If the leak is found to be within a cryomodule, it  will have to be
removed and replaced with one of the modules removed during the
Summer.   This would also mean that another week of delay in the
startup.    Enough information to make a decision on removing a module
(or not) will be available in the next several days.

The Halls run coordinators were informed this morning to cancel shifts
up to next Friday.

Arne

--
Arne Freyberger
Director of Accelerator Operations
Jefferson Lab           Office: (757) 269-6289
12000 Jefferson Avenue    Cell: (757) 876-6289
Newport News, VA 23606   Email: freyberg at jlab.org<mailto:freyberg at jlab.org>




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