[Clas12_rgb] experiment news

[Marco Contalbrigo]

Dear all,
I am available this afternoom. Bests, Marco.

On Tue, 5 Mar 2019, silvia at jlab.org wrote:

> Dear all,
> as you will soon read officially from the PDL, all RG-B shifts are
> canceled from today at 9AM until at least owl shift on Thursday. The
> reason for this is the following: the accelerator has been struggling in
> the last week to deliver ~10.6 GeV energy. The trip rate is very high, and
> down times are extremely frequent. As an example, we basically managed to
> take two runs since beam-studies ended yesterday at noon and this morning.
> In spite of our effort to fight for the maximum energy (which is crucial
> for the J/psi experiment), this morning we were told that the accelerator
> will lower the energy down to 10.2 GeV, in order to see if the
> performances improve. They will work on this until the end of Thursday day
> shift.
> This means, in a very optimistic view, 2.5 days lost, and, in a more
> realistic view, at least 3 if not more.
> I asked the PD this morning, he says that the 2-pass RF seperator test
> planned for today will still be carried on. However, there are chances
> that the Monday and Tuesday down times for beam studies and RF recovery,
> that should have accomodated the energy-change to go to 2-passes for BAND,
> may not happen.
> Considering the amount of time we have lost until now for beam-related
> issues, trip rates, down time, the lost day of this past weekend, two 3
> days lost from now to Thursday, and the two days likely lost on March
> 18-19, I personally feel that fighting to keep up the plan of running at
> low beam energy on Monday 11th is not a good idea. If accelerator proposes
> us to cancel all interruptions and get normal beam instead, we should go
> for it.
> The PD will inform me of the outcome of the RF-separator 2-pass test
> probably by lunch time today.
> I would like to propose to find some time to discuss this afternoon with
> the BAND group to understand how crucial this low-energy run is for the
> time being, the possibility to postpone it to the fall, etc.
> Please let me know if/when you are available. Given the current stop of
> the experiment, my own schedule is pretty flexible.
> Best regards,
> Silvia
>
>
>
>
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