Richard is correct. We do have a polarized target of anywhere from 65%
to 75% (to be more precise within this range we need more involved
analysis). I'm monitoring this day by day and I believe that I showed
collaboration evidence of a target vector polarization. There is also
evidence of strong tensor polarization though more work is needed on
this channel. I believe that when all said and done all of the data
will have to be cut on cerenkov anyway, so we loose little when we put
cerenkov into the trigger (we do loose channels with no electron in the
final state). Also, I looked at hydrogen runs we took few days ago to
see if we reconstruct beam energy correctly. We do if the electron is
on the right and with electron on the left a correction to an electron
momentum of 5% is needed (~40 MeV). However, resolution is still subpar
(~50 MeV) and needs to be addressed.
Cheers, Vitaliy
Michael Kohl wrote:
>For some reason, the previous two messages from Tancredi and Richard were
>not sent to elog nor blast_shifts which I redo now.
>
>MK
>
>
>
>
>---------- Forwarded message ----------
>Date: Fri, 5 Mar 2004 12:06:19 -0500 (EST)
>From: Richard Milner <milner@mitlns.mit.edu>
>To: Tancredi Botto <tancredi@lns.mit.edu>
>Cc: John Calarco <jrc@einstein.unh.edu>, Michael Kohl <kohlm@mit.edu>,
> "Milner, Richard" <milner@lns.mit.edu>,
> "Hasell, Doug" <hasell@lns.mit.edu>,
> "Tsentalovich, Genya" <evgeni@mit.edu>,
> "Turchinetz, Bill" <billt@lns.mit.edu>
>Subject: Re: [BLAST_SHIFTS] [BLAST_ANAWARE] more deadtime
>
>
>By prescaling the inclusive severely we are left with the central channels
>for BLAST (e,e'p) (e,e'n) (e,e'd) for both vector and tensor. The
>priority (particularly for the students assigned thesis topics) is to
>produce scattering asymmetries from analyzed data. I have seen vector
>(e.e'p) asymmetries which tells us the target is vector polarized to about
>70%. These results comes in quickly and (if it isn't) should be monitored
>at least on a daily basis. We have lots of neutron data (from electrons
>detected on the left side until the right side 2nd level trigger was
>found unplugged) and (once the neutron offsets are implemented) we should
>start to see (e,e'n) vector asymmetries. I have not seen any analysis of
>the tensor results that make sense.
>
>In parallel, we must attack the deadtime problem. The (e,e'n) channel is
>limiting the livetime. Thus, tightening the electron identification
>in this trigger and further lead shielding in front of the forward LADS can
>only increase the livetime.
>
>Richard
>
>
>
>On Fri, 5 Mar 2004, Tancredi Botto wrote:
>
>
>
>>While I agree on the big picture here my problem is a lot simpler:
>>
>>I haven't seen a strong proof of target polarization, we are not at the
>>level we were in december, we have had a much more fragmented running so
>>far. Nothing wrong, we are just moving on. Should we pursue this by
>>throwing away 30% of our first asymmetry data at low Q2 ?
>>
>>My rationale here is to establish the experiment. I am not taking
>>shortcuts, rather I am concerned about "efficacy". Sure I throw away
>>stuff: it is just what I want to do to concentrate on the quality of
>>the vector and tensor ABS states. Nobody else has measured it, have we ?
>>
>>I would love to fix the deadtime/2nd level-trigger/beam-tune problem now,
>>but I can't. Between now and that moment I think we should maximize the
>>reactions that are most important in proving the experiment exists. It
>>would also give the strong signal that we want to take data NOW, not
>>try another step of development.
>>
>>Once we make that step I'd be delighted to consider many other
>>possibilities. Regards,
>>
>>tancredi
>>
>>
>>
>>
>
>
>
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