[Tpe] TPE experiment readiness
Larry Weinstein
lweinste at odu.edu
Thu Apr 1 15:12:56 EDT 2010
Dear Volker,
Thank you for your candid response to our exchange. We realize that TPE
will only run if HDIce cannot. However, we were under the impression
that the decision had already been made that TPE would run first if
HDIce was delayed.
No matter which experiment runs in September, the sooner a decision is
made, the more resources will be available. This is especially true for
our collaborators at Argonne and Valparaiso who have significant
administrative restrictions. The TPE run is sufficiently important that
two of us, Brian and myself, have scheduled our rare and precious
sabbaticals for Fall 2010, just in case TPE runs.
We completely agree with you that TPE cannot be allowed to damage the
CLAS detectors. We are now modeling the radiation dose to the tagger
scintillators. The 3% DC occupancy is a hard limit. We will not exceed
that. Period. Note that the luminosity for 4 GeV and higher electron
experiments is limited by the 3% Region 1 DC occupancy limit. Our
experiment will be similarly limited. If anything, we will cause less
radiation damage to the drift chambers than standard electron runs
because the occupancy will not be concentrated in the forward wires of
Region 1 but will be more evenly distributed. The reason that it took
almost three years after the test run to demonstrate the TPE feasibility
is that we are not willing to exceed the 3% DC limit.
We were not aware of the need for a technical review panel. If we had
known this, we would have requested a review panel last year. We would
greatly appreciate scheduling the review for sometime in May so that we
can prove our readiness.
With the limited amount of beam time available in the 6 GeV era, it is
important to maximize the impact of that beam time. I realize that the
lab has invested a tremendous amount of effort into doing just that.
This means that lengthy installations should take place during long down
times, higher priority experiments should run earlier, and experiments
with external competition should also run earlier. TPE was originally
scheduled last because a) we had not yet demonstrated that the
experiment was feasible, b) we did not have any competition yet, and c)
it was assumed that HDIce would be ready. The first two conditions have
changed and the third is not certain.
Sincerely,
Larry Weinstein for the TPE collaboration
-------- Original Message --------
Subject: Re: [Tpe] Mont's presentation to JSA
Date: Thu, 25 Mar 2010 18:03:34 -0400
From: burkert <burkert at jlab.org>
To: weinstein at odu.edu
CC: tpe <tpe at jlab.org>
Hello,
you guys shouldn't get too excited about all this.
First of all, TPE was never scheduled to run this fall, and just
pretending it was doesn't make it true. However, I am indeed considering
this as one of two options in case HDIce isn't ready, and only then! The
determination that HDIce will not be ready cannot be made much earlier
than at the end of May, or early June. If the TPE run is so important
(which I think it is) then you guys should be able to adjust your
schedules accordingly.
We at Jlab are currently planning ahead to modify the beamline and
shielding configuration during the 6 weeks summer down, in case TPE will
be substituting for HDIce. The 6 weeks is all the time we have
available. If your travel plans conflict with that, that is too bad.
The other option we consider is running PRIMEX II. These folks seem to
have fewer problems in being available to prepare the run. In fact,
they already got their calorimeter fully checked out during the spring
down time, and they have the advantage that less effort is required to
get this experiment ready.
There are a number of things that we need to have checked from the TPE
group. The large luminosity gap from the test run needs to be
demonstrated to a review committee to have been closed (I have seen the
rreport where the claim is made. This is a good start, but is not
sufficient). The radiation dose level at the focal plane that I
mentioned to Dave as a potential problem, needs to be studied (Pawel
from RadCon may be able to help). The protection of the drift chamber
system is another concern. We will have stringent upper limits in
occupancies during the run.
In general, we should not display an attitude that we don't care what
experiment comes after us, because TPE is so much more important than
others.
Again, according to our current schedule TPE can only run if HDIce is
not ready. If you want to change the priority you need to convince other
people.
Volker
Brian A Raue wrote:
> Hi All,
> From my point, it is crucial that a decision regarding the running of
> TPE this fall be made as soon as possible. I have been awarded a
> sabbatical for the fall in the anticipation that we will run. If not, I
> have to either reschedule the sabbatical or find something else to do soon.
> Further, I have a grad student now working on the experiment. If we
> don't run then I need to find him another project. It is unfair to the
> student for him to spend a significant amount of time preparing for TPE
> only to have it pulled out from under him.
>
> Brian
>
> Larry Weinstein wrote:
>
>> Dear TPEers,
>>
>> There was an interesting paragraph in Mont's March 10 JSA presentation
>> (slide 21, titled 'FY11 Guidance Scientific Objectives'):
>>
>> Hall B:
>> • Complete data taking on N* with polarized HDIcetarget (especially
>> neutron
>> data). Note original plan was to complete this experiment in FY11;
>> it will likely
>> be delayed, and we may try to advance PRIMEx-II into this period
>> instead if
>> adequate equipment funding is available
>>
>>
>> It is interesting a) that HDIce uncertainties are already known at the
>> director's level and b) that Primex is still listed as the most likely
>> experiment to run in its place.
>>
>> --
>> Sincerely,
>> Larry
>>
>> -----------------------------------------------------------
>> Lawrence Weinstein
>> University Professor
>> Physics Department
>> Old Dominion University
>> Norfolk, VA 23529
>> 757 683 5803
>> 757 683 5809 (fax)
>> weinstein at odu.edu <mailto:weinstein at odu.edu>
>> http://www.physics.odu.edu/~weinstei
>>
>>
>> ------------------------------------------------------------------------
>>
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>> https://mailman.jlab.org/mailman/listinfo/tpe
>>
>
>
>
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