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Re: list of assignments for bcal decision
Hi George
Sure thing - you did mention the 20 MeV threshold in your note and
from your numbers the expected number of photoelectrons assuming
20% PDE is 40 or equivalent to about 2.5 p.e. for a standard vacuum
tube. Your comment about cabling and impact on seeing 20 MeV
is very relevant. I will try to get some of those acceptance numbers
vs min energy out soon.
Cheers
Alex
At 11:03 AM -0600 4/13/07, George Lolos wrote:
>Hi Elton:
>
>I did not have time yet to look at your posting, I will do later today.
>I assume you didn't have time to read the draft I sent you yesterday.
>We can address those on Monday.
>
>The threshold of 20 MeV, needs to be investigated particularly so in
>terms of the approximate 2 radiation lengths of cables from the
>chambers. In my report, I explicitly mention the 20 MeV threshold in
>terms of the energy deposition in the SciFi's (~2.4 MeV) and the
>resulting numbers of P.E.'s in the SiPM's.
>
>I agree that SensL will not take part in our discussions and I don't
>think they would do this even if we asked them to. I also think that
>the opportunity for us as a group to invite them to attend a specific
>session, the emphasis is on the invitation and specific session, is
>invaluable for the rest of the working group to hear first hand where
>they are in terms of the R&D and further progress, costs and everything
>we feel it's important for us to know. We therefore have to decide among
>us on Monday when is the optimal time for such session and communicate
>this to SensL. I would think that the second session on Monday morning
>may be a good time, we would have the first session to get the questions
>together and look at the road map. Elke's suggestion for the afternoon
>on Monday is also a good alternative, if their travel plans allow it.
>
>George
>
>>>> Elton Smith <elton@jlab.org> 04/13/07 8:10 AM >>>
>
>HI George,
>
>I have posted an update to the note on specifications and evaluation of
>readout options (GlueX-doc-795). Before you get too excited: this is
>just
>a draft and I am trying to prepare a framework for evaluating various
>options. The numbers I have included need to checked and we need to
>discuss whether my logic is appropriate. These issues also need to be
>considered along with the information you are putting together.
>
>One particular issue that I became aware of is that many of the
>requirements are driven by conditions at the nominal threshold of 20
>MeV.
>We can discuss the implications of this requirement on Monday at our
>phone
>conference.
>
>We also need to think about an goals and agenda for the workshop Apr
>23-24. It appears that we will have visitors from SensL, but I do not
>think they should participate in all our discussions, although their
>input
>would be very valuable. Elke has suggested to meet with them on Monday
>afternoon after we have had some time for internal discussions in the
>morning. We also need to schedule video conference sessions where others
>can participate remotely (e.g. Christina and Richard + others).
>
>Cheers, Elton.
>
>
>> Christine
>> > HI George,
>> >
>> > See below:
>> >
>> >
>> > On Wed, 11 Apr 2007, George Lolos wrote:
>> >
>> >> Hi Elton:
>> >>
>> >> A couple of comments with regards to your e-mail below:
>> >>
>> >> 1. The review (teleconference I presume) next Monday is a good idea
>and
>> >> we will participate from Regina.
>> >
>> > We are planning for 1:00 pm on Monday.
>> >
>> > To connect by telephone:
>> >
>> > 1.) dial:
>> > 800-377-8846 : US
>> > 888-276-7715 : Canada
>> > 302-709-8424 : International
>> >
>> > 2.) enter participant code: 39527048# (remember the "#")
>> >
>> >>
>> >> 2. I thought that the meeting on the 23rd is not to make any
>decision
>> >> regarding the BCAL read-out, but instead we will discuss in great
>> >> technical details the various options (SiPM's, Planacons and mesh
>> >> PMT's). Yet you refer to a decision that gets my blood flowing.
> > >> Anything changed or it was a Freudian slip? :-)
>> >>
>> > What we present at the Lehman review this June and how this is
>presented
>> > must definitely be decided. We are already turning in budget
>estimates
>> > based on assumptions of the readout, and we need to be able to back
>them
>> > up with quantitative arguments.
>> >
>> > In addition need to satisfy one of our internal milestones for FY07
>which
>> > is a "decision on the readout for the barrel calorimeter." This was
>> > presented at the last Lehman review and is also shown as slide #6 in
>the
>> > manpower and budget presentation that Elke showed the collaboration
>less
>> > than two weeks ago (see
>/group/halld/INFO-FOR-COLLAB/Budget_manpower.ppt)
>> >
>> > Also, the deadline for the following Recommendation #27 IPR (2005)
>Sec 2.5
>> > is June 2007:
>> >
>> > "Develop a plan for readout of GlueX barrel calorimeter based upon
>> > conventional photomultiplier tubes. The plan should include fiber
>> > routing, end iron configuration, shielding, and cost estimate."
>> >
>> > So, yes, decisions need to be made. Are they final? No, but the
>longer we
>> > wait the harder they are to change, and we must make our best effort
>to
>> > make the best and most informed decisions possible.
>> >
>> >> 3. I have received notification from SensL that a couple of their
>people
>> >> will be able to visit JLab next week and perhaps be able to take
>part in
>> >> some of the discussions on the April 23-24. I would strongly
>encourage
>> >> this possibility to hear from the source directly the update and be
>able
>> >> to ask all the specific questions we need. This partly addresses
>your
>> >> suggestion of persons outside the project. What other names do you
>have
>> >> in mind and what is their role or expertise? Meetings that have
>too
>> >> many persons involved get cumbersome and not as productive as
>smaller
>> >> groups of persons directly in the know. On the other hand, we
>don't
>> >> want to exclude anyone with specific knowledge on field resistant
>> >> sensors and electronics expertise. Please, don't invite Domingo
>and
>> >> others just for an audience and ideas on the fly.
>> >>
>> > We have not heard anything about anyone from SensL visiting JLab,
>and we
>> > want to make sure that their time he is productive. So they should
>let us
>> > their schedule ASAP. Depending on who is coming and their expertise
>> > (technical? sales?), it may or not be appropriate for them to
>participate
>> > in our discussions.
>> >
>> > One of the single most important numbers we need from them (an
>informal
>> > budgetary estimate is fine, but needs to written down) is the cost
>per
>> > channel of SiPMs in production (including all auxiliary
>> > mounting/electronics/etc that would be necessary for a particular
>> > configuration).
>> >
>> >> 4. Before Zisis and George commit themselves to yet another
>document,
>> >> please have a look at 739, 708 and 664 (all by Zisis) and see if
>the
>> >> info is not already there. I am also working on a detailed report
>> >> showing BCAL response to photons, spectra and read-out segmentation
>and
>> >> how it matches the SiPM parameters. Manpower at the UofR is so
>tight
>> >> now, any duplication of effort on material already readily
>available
>> >> will only make things worse on other fronts.
>> >>
>> > I hear you. I will try to collect together the necessary info.
>> >
>> >> The topics you listed look fine to me.
>> >>
>> >> So sprach Georg
>> >>
>> >> George
>> >>
>> >>
>> >>
>> >> >>> Elton Smith <elton@jlab.org> 04/11/07 6:04 AM >>>
>> >>
>> >> Hi Bcal enthusiasts,
>> >>
>> >> I would like to reserve an hour on Monday afternoon (I suggest 1:00
>pm)
>> >> to
>> >> review issues that need addressing before the Bcal decision meeting
>the
>> >> following week. Below is a list of issues that need updates. I have
>put
>> >> some names down on the likely candidates for reporting on these.
>> >>
>> >> It might also be useful to go over the format/schedule for the Bcal
>> >> review
>> >> (times, format, etc). Do we want to ask a couple of persons which
>are
>> >> not
>> >> direcly in the project to give us some feedback?
>> >>
>> >> I would also ask George/Zisis to prepare a 1-2 page table of Bcal
>design
>> >> parameters in a format similar to what was done for the drift
>chambers
>> >> before the DC review (See for example GlueX-doc-740). We will need
>this
>> >> for all subsystems in preparation for CD-2, so this is a good time
>to
>> >> create it for the Bcal. (This information is in various documents
>and it
>> >> will be useful to summarize it into a couple of pages).
>> >>
>> >> Topics (please send me items that are missing)
>> >>
>> >> 0. How to summarize how physics needs drive the design specs
>> >> - energy resolution
>> >> - energy threshold
>> >>
>> >> 1. SiPM
>> >> - linearity/dynamic range
>> >> - need for amplification
>> >> - need for cooling?
>> >> - measurements of dark rate (Carl)
>> >> - spectrum of dark noise (Carl)
>> >> - lifetime (DESY experience) (George)
>> >> - outline of single electronics channel
>(LV/disc/signal/etc)
>> >> (George/Zisis)
>> >> - budgetary estimate from SensL
>> >>
>> >> 2. Planacon
>> >> - amplifier/shaper (Carl/Vladimir?)
>> >> - light guide design / optics of light collection of WC into
>> >> fibers (George?)
>> >> - placement
>> >> - B-field map of fringe field (David)
>> >> - lifetime
>> >> - measurements of dark rate (Carl)
>> >>
>> >> 3. Wire Mesh
>> >> - use in combination with SiPMs?
>> >>
>> >> --
>> >>
>> >>
>> >
>> >
>>
>>
>>
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Alex R. Dzierba
Chancellor's Professor of Physics (Emeritus)
Department of Physics / Indiana U / Bloomington IN 47405 / 812-855-9421
JLab Visiting Fellow
Jefferson Lab / 12000 Jefferson Ave / Newport News, VA 23606 / 757-269-7577
Home Phone: 812-825-4063 Cell: 812-327-1881 Fax: 866-541-1263
http://dustbunny.physics.indiana.edu/~dzierba/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~