[Halld] Potential continuation of commissioning at 6 GeV endpoint

[Eugene Chudakov]

Update on the run status:

The Lab is planning to run at a lower energy for the rest of this run.
For Hall D it would be about 5.5 GeV (some fine tuning may happen).
There is no change so far on the cutoff date (May 4). The North CHL
(CHL-1) decontamination seems to be going well. They are planning to
start the CHL-1 pumping on Apr 8. The beam may appear on Apr 11.

Regards,
Eugene


On Mon, 30 Mar 2015, Eugene Chudakov wrote:

> Dear colleagues,
>
> As a result of the power outage on Mar 25 the accelerator has serious
> problems. Most likely, it would be able to provide only a ~6GeV beam
> for the rest of the Spring run.
>
> There are two 2K helium liquifiers (CHLs) servicing two accelerator
> linacs. The Northern CHL is tripping because of a differential
> pressure increase at some element. The problem is attributed to ice
> (some contamination frozen). They are going to warm it up to get rid
> of the ice. It will be done by Friday. There is a good chance that the
> CHL will be able to run at 2K after that. The Southern CHL
> demonstrates a serious mechanical failure in one of the
> compressors. If true, the repair may take weeks/months. One working
> CHL can provide only a ~6GeV acceleration.
>
> We expect that by Wednesday the Lab will decide on the path forward -
> whether to run at 6 GeV and whether to extend the run beyond the
> current cutoff at May 4.
>
> The HPS experiment in Hall B uses a low energy and would probably
> benefit from the 6 GeV run. The Hall A DVS experiment would probably
> not. We have to decide if we would like to run and what the program
> would be.
>
> Certainly, a part of the Hall D commissioning can be done at 6 GeV, in
> particular the wire chambers work, some calorimeter calibration and
> some DAQ work. We need to prepare by Wednesday a preliminary
> objectives for such a running and consider possible implications (say,
> a larger relative noise in the trigger). We are planning to start such
> discussion at 8:45 meeting on Wednesday.
>
> Regards,
> Eugene
> ------------------------------------------------------
>
> Eugene Chudakov
> https://userweb.jlab.org/~gen/
> phone (757) 269 6959  fax (757) 269 6331
> Thomas Jefferson National Accelerator Facility
> 12000 Jefferson Ave, STE 4,
> Newport News, VA 23606 USA
>