Dear All,
With respect to the trigger discussion I think we are compromising the
efficiency of the experiment if we do not use the Cerenkovs in the trigger.
I remind you that at NIKHEF (same experiment, same target, same acceptance)
we had to use the Cerenkovs in the electron trigger, there was no choice.
Ricardo
On 3/5/04 11:09 AM, "vitaliy ziskin" <vziskin@mit.edu> wrote:
> 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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