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Re: cost estimates - more questions
Thank you,Elton.As I quote in the document the cost is about 3,000$/tube
but the Hamamatsu people were eager to talk to me about a month ago when I
was at CERN and through e-mail they essentially asked what price would WE
like!But I have not pushed for the meeting since there was no
encouragement from the collaboration.
Chers,Christine
>
> Hi Christina,
>
> We want as many people as possible to contribute. I will add a section on
> the finemesh pmts. (Note that it is already collected in the references,
> althougth I have not had time to add it to the text.)
>
> Could you send me cost estimates for the tube?
>
> Thanks, Elton.
>
>
>
>
> Elton Smith
> Jefferson Lab MS 12H5
> 12000 Jefferson Ave
> Suite # 16
> Newport News, VA 23606
> elton@jlab.org
> (757) 269-7625
>
> On Thu, 5 Apr 2007, Christina Kourkoumeli wrote:
>
>> Dear ElKe and George,
>> I have been folowing this exchange of mails and my colleagues and I
>> would
>> be very interested in participating in the read-out workshop since we
>> have
>> spend quite few months thinking and working on it.
>> By simulations of the shower profiles, which were performed in Athens as
>> well, we concluded in a Document submitted few months ago that 210
>> channels for the outer section are more than enough (Doc 731-v1) and
>> moreover we recommended for these the use of finemesh PMT's.
>> I have the feeling that if we go for SiPM's in the inner layer .it is
>> reasonable to use conventional PM's at the outer.And from the B-field
>> measurements,I find that fine-mesh are far more superior in their
>> (non)-sensitivity than Planacons.
>> Please keep this document and the relative option in the loop.
>> Cheers,
>> Christine
>>
>>
>> > On Wed, 4 Apr 2007, Elke-Caroline Aschenauer wrote:
>> >
>> > Dear George,
>> >
>> > sorry more questions, hopefully not to stupid ones.
>> >
>> > But first the good news removing discriminators and tds from the outer
>> > calorimeter saves 240000k$
>> >
>> > I know you are planning for a test stand for the sipmt-arrays.
>> > If we go with the LV distribution version ala ILC, to apply the
>> correct
>> > resistor for each sipmt-array we need to know the bias corresponding
>> to
>> > certian gain like 1*10^6 befeore building the distribution chain.
>> > Have you been planning on measuring the gain vs bias for the arrays in
>> > your test stand. This can be quite an effort.
>> >
>> > Even if we put the gain correction factors in the flash, we might want
>> to
>> > start from a rougly equal distribution to not loose to much dynamik
>> range
>> > of the fadc, so it would be good to have the measurement.
>> >
>> > For the rest we can actually nicely monitor gain changes with time
>> with
>> > the response for minimum ionizing particles and can account for them
>> in
>> > the fadc
>> > to have a good trigger input.
>> >
>> > Go this route we will safe 600000 k$ on HV-boards, of course building
>> the
>> > distribution system cost something and the test stand to measure gains
>> vs
>> > bias voltage.
>> >
>> > Tell me what you think about my thoughts, I hope they are not to
>> st.....
>> >
>> > Cheers elke
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >> Date: Wed, 4 Apr 2007 19:01:25 -0400 (EDT)
>> >> From: Elke-Caroline Aschenauer <elke@jlab.org>
>> >> To: George Lolos <George.Lolos@uregina.ca>
>> >> Cc: halld-cal@jlab.org, Eugene Chudakov <gen@jlab.org>,
>> >> "zisis@uregina.ca" <zisis@uregina.ca>
>> >> Subject: Re: cost estimates
>> >>
>> >> On Wed, 4 Apr 2007, George Lolos wrote:
>> >>
>> >>
>> >> Hi George,
>> >>
>> >> thanks for the quick answers, they help me quite a bit. I have some
>> >> remarks below.
>> >>
>> >> >
>> >> > Hi Elke:
>> >> >
>> >> > I will try to address the questions individually, below:
>> >> >
>> >> >
>> >> > Elke-Caroline Aschenauer wrote:
>> >> >
>> >> > >Dear George and Zisis,
>> >> > >
>> >> > >by trying to come up with the final numbers for the budget, we
>> over
>> >> run by
>> >> > >2M$ in procurement and an other 1.5M$ worse of manpower some
>> >> questions
>> >> > >came up.
>> >> > >
>> >> > >And please don't count any of my questions as an attack against
>> >> SiPMTs or
>> >> > >the bcal or ....
>> >> > >I only try to get numbers straight and answers to unpleasant
>> >> questions
>> >> > >which will come.
>> >> > >
>> >> > >
>> >> > Come now Elke, it's only money and it's other people's money :-)
>> >> ........
>> >> >
>> >>
>> >> hmhm, my tax money goes somehow in, but it is good spent on a FADC
>> for
>> >> the
>> >> bcal, so indeed I don't worry to much about it. :)
>> >>
>> >>
>> >> > >1. do we really need CFDs for the outer barrel, what is the
>> advantage
>> >> for
>> >> > > the TOF
>> >> > >
>> >> > >
>> >> >
>> >> > Not at all. In fact, in my logic that I had expressed in a couple
>> of
>> >> > reports earlier, was that CFD's only make sense for the first few
>> >> inner
>> >> > layers where charged particle and critical photon reconstruction
>> >> > information is derived from. It makes no sense, whatsoever, to
>> >> > instrument all channels with CFD's. If we go with flash ADC's, all
>> >> the
>> >> > other channels past the first 5 layers don't even need TDC's.
>> >> >
>> >> perfect, so I asume no cfds and tdcs for the outer barrel.
>> >>
>> >> >
>> >> >
>> >> > >2. currently we instrument the bcal with 4224 channels SiPMTs 1920
>> in
>> >> the
>> >> > > inner and 2304 in the outer,
>> >> > > we say we combine 2 channels in the other for the electronics
>> so
>> >> we
>> >> > > have
>> >> > > 1920 + 1152 channels of CFD (100$/ch), F1TDC(100$/ch) and FADC
>> >> (250$/ch)
>> >> > > of course combining things even more in the outer BCAL, will
>> safe
>> >> > > money, but of course and I know we don't have a good answer yet
>> >> what is
>> >> > > possible.
>> >> > >
>> >> > >
>> >> >
>> >> > The number of 1920 corresponds to five inner layers. I feel
>> >> > uncomfortable if we base all our photon trajectory reconstruction
>> on
>> >> > five layers only. Maybe I am overly conservative but perhaps
>> adding a
>> >> > sixth layer to bring us to a 12 cm individually instrumented depth,
>> is
>> >> > something we may wish to consider. This is a minor point and we
>> will
>> >> > need serious MC simulations to see what we lose or gain, if any.
>> >> >
>> >> > As one can see from the energy deposition profiles we have
>> simulated
>> >> for
>> >> > the BCAL, even for a 1 GeV photon entering perpendicular to the
>> BCAL
>> >> (a
>> >> > situation as limiting as it gets) the number of photons collected
>> past
>> >> > 15 cm depth is much smaller than what has been collected between
>> 4-12
>> >> > cm. If we combine every two read-out cells in the outer layers we
>> >> will
>> >> > certainly not lose trajectory information because most photons of
>> some
>> >> > energy to penetrate that deeply will also come at forward angles,
>> >> > predominantly. In fact, past 16 cm depth or so, in other words
>> past
>> >> > the eighth cell from the inner face, even four cells combined will
>> >> most
>> >> > likely not degrade us at all. When we meet for the SiPM workshop,
>> I
>> >> > will show all these profiles and I will also send them to you by
>> the
>> >> end
>> >> > of the week, I hope, so we can discuss this with more info in front
>> of
>> >> > all of us.
>> >> >
>> >> > The bottom line is that combinations of two and/or four can be done
>> >> and
>> >> > should be pursued not only for cost savings but for simplicity of
>> data
>> >> > handling as well. For the layers past 15 cm, there will be so few
>> >> > photons per cell most of the time, we are wise to combine outputs
>> of
>> >> > four cells.
>> >>
>> >>
>> >> okay, lets stick with for the moment until we have more simulations,
>> >> with
>> >> excha channel a Fadc in the outer and combine 2 for the inner.
>> >>
>> >> >
>> >> >
>> >> > >3. now the LV for the SiPMTs, we need bias voltage LV<50V and
>> 10-20
>> >> nuA/ch
>> >> > > the questions to answer are do we need in individual bias for
>> each
>> >> > > SiPMT array?
>> >> > > if no how many can we combine, are there measurements which
>> show
>> >> gain
>> >> > > for several individual SiPMTs?
>> >> > > If we could combine LV-channels what is the granularity? do we
>> >> need
>> >> > > a resistor change to correct for different bias voltages
>> needed,
>> >> do the
>> >> > > gains change with time, so we have to adjust the adjustments.
>> >> > >
>> >> > >---> I know that are a lot of questions and I appreciate answers
>> are
>> >> very
>> >> > > difficult to give but the LV is worse 4224*150=634k$
>> >> > >
>> >> > I had answered this question already to Fernardo, I think. The
>> answer
>> >> > is we don't need to control the voltage to each array. The process
>> >> > developed by SensL is such that the variations in breakdown voltage
>> >> > between different batches of Si wafers is less than 1 V and the
>> real
>> >> > range of variation is closer to 0.1- 0.2 V. So, the idea is that
>> we
>> >> > select arrays with breakdown voltage within that small tolerance
>> level
>> >> > and we control them with a common supply voltage. I suspect that
>> we
>> >> > will have a large number of arrays, each requiring the same
>> voltage,
>> >> but
>> >> > we clearly have to limit the number per P/S for other reasons.
>> Each
>> >> P/S
>> >> > will be identical to all the rest with only a very small adjustment
>> >> > range of say 2V. How may we will need? I think this is a question
>> of
>> >> > the electronics guys to tell us based on current and stability
>> >> > requirements. The ILC group at DESY has developed such systems for
>> >> the
>> >> > thousands of 1 mm2 SiPM's they use and with much greater voltage
>> >> > adjustment requirements, can't we get some info from them on their
>> >> design?
>> >> >
>> >> > If we can control 16 arrays per P/S, then the number drops down to
>> 264
>> >> > and I believe we should eb able to drive 16 arrays for each, right?
>> >> By
>> >> > the way, the SensL arrays are more in the 30 V range not as high as
>> 50
>> >> V.
>> >> >
>> >>
>> >> I know that the breakdown voltage is only around 30V, but 50V as max
>> >> will
>> >> not make a difference in the cost and is a nice number.
>> >> But let me ask some more questions. I know you said the breakdown
>> >> voltage is very similiar for sipmts with production process sensl
>> wants
>> >> to use. No problem I can accept this, but if you use this to combine
>> HV
>> >> channels you make the implicit assumption that there is a 100% direct
>> >> connection betwen the breakdown voltage and the gain of a SiPMT. Do
>> we
>> >> know this as a fact. I know you are aware of this but we cannot
>> >> tolerate to big differences in gain because of the trigger. Or we put
>> a
>> >> gain correction factor in the FPGA of the FADC, to apply a gain
>> >> correction
>> >> before the summing.
>> >>
>> >> I can ask chris this is an option.
>> >> I agree with you that you can build a distribution system which takes
>> >> care about small channel to channel variations, and if we can apply
>> gain
>> >> factors in FADC even different time constants in ageing are to
>> relevant.
>> >> The only open question would be the effect on the TOF performance.
>> >>
>> >> I will ask at DESY to see what their experience is also they have
>> >> studied
>> >> the variation in gain for different SiPMTs with the same bias
>> voltage.
>> >> I keep you in formed, what I find.
>> >>
>> >> > >
>> >> > >4. there is also the question where to but the cfds and where to
>> do
>> >> the
>> >> > > summing. Cables are also an issue.
>> >> > > If we would but the CFDs next to the SiPMTs we need double the
>> >> amount
>> >> > > of cables 8000 instead of 4000, I think that is not an option,
>> >> summing
>> >> > > the outer BCAL channels by 2 directly next to the SiPMTs will
>> only
>> >> safe
>> >> > > 1000 cables.
>> >> > > ----> so I think we have to put the CFDs after the cables
>> >> > > ----> comments
>> >> > >
>> >> > >
>> >> > With the outer layer SiPM arrays combined in two's and/or four's,
>> we
>> >> > don't even want to use CFD's but we certainly want to discriminate
>> >> them
>> >> > since most of the cells will add zero signal but will contribute DR
>> >> > P.E.'s. This discrimination can happen after their combination at
>> >> some
>> >> > level, say 10 P.E.'s (about 260 keV in energy deposition). For
>> the
>> >> > inner layers is there such a problem with cables? If yes, then we
>> can
>> >> > indeed discriminate them when the analog signal cable reaches the
>> >> > electronics racks.
>> >> >
>> >>
>> >> ups, here you lost me. If I don't use the outer bcal for tof, I also
>> >> need
>> >> any discriminator on it or do I miss something. The FADC of course
>> would
>> >> is untouched.
>> >>
>> >>
>> >> I will implement the changes for the cfd's and also the f1tdc.
>> >> For the LV I would like to see what they say at DESY.
>> >>
>> >>
>> >> Cheers elke
>> >>
>> >>
>> >> > I hope I have answered most of them in an informative way,
>> >> >
>> >> > Cheers,
>> >> >
>> >> > George
>> >> >
>> >> >
>> >> >
>> >> >
>> >>
>> >> ( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
>> >> ) `\ -
>> >> / '. | +
>> >> | `, Elke-Caroline Aschenauer =
>> >> \,_ `-/ -
>> >> ,&&&&&V Jefferson Lab +
>> >> ,&&&&&&&&: HALL-D 12C / F381 121-A Atlantic Avenue =
>> >> ,&&&&&&&&&&; Mailstop: 12H5 Hampton, VA 23664 -
>> >> | |&&&&&&&;\ 12000 Jefferson Ave +
>> >> | | :_) _ Newport News, VA 23606 Tel.: 001-757-224-1216 =
>> >> | | ;--' | Mail: elke@jlab.org Mobil: 001-757-256-5224 -
>> >> '--' `-.--. |
>> +
>> >> \_ | |---' Tel.: 001-757-269-5352
>> =
>> >> `-._\__/ Fax.: 001-757-269-6248
>> -
>> >> +=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+
>> >>
>> >>
>> >
>> > ( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
>> > ) `\ -
>> > / '. | +
>> > | `, Elke-Caroline Aschenauer =
>> > \,_ `-/ -
>> > ,&&&&&V Jefferson Lab +
>> > ,&&&&&&&&: HALL-D 12C / F381 121-A Atlantic Avenue =
>> > ,&&&&&&&&&&; Mailstop: 12H5 Hampton, VA 23664 -
>> > | |&&&&&&&;\ 12000 Jefferson Ave +
>> > | | :_) _ Newport News, VA 23606 Tel.: 001-757-224-1216 =
>> > | | ;--' | Mail: elke@jlab.org Mobil: 001-757-256-5224 -
>> > '--' `-.--. | +
>> > \_ | |---' Tel.: 001-757-269-5352
>> =
>> > `-._\__/ Fax.: 001-757-269-6248
>> -
>> > +=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+
>> >
>> >
>>
>>
>>
>
>