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Re: cost estimates - more questions
Dear Elke,
Thanks for your invitation but I think that is very hard to partecipate in
person.I am returning to Athens from Gva on the 21st and have no budget
for overseas traveling.Nevertheless,if we manage to have the EVO
connection up like we almost did last time,I am willing to stay till late
(midnight?)in my office and virtually partecipate.
Happy Easter to everybody !!
Christine
> On Thu, 5 Apr 2007, Elton Smith wrote:
>
> Dear Christina,
>
> I can only say the same as elton of course your are more than welcome to
> participate and even more contribute to the discussion.
> Would you be able to maybe come to JLAB for this meting. I think that
> would be nice.
>
> Cheers elke
>
>
>> Date: Thu, 5 Apr 2007 07:55:38 -0400 (EDT)
>> From: Elton Smith <elton@jlab.org>
>> To: Christina Kourkoumeli <hkourkou@phys.uoa.gr>
>> Cc: Elke-Caroline Aschenauer <elke@jlab.org>,
>> George Lolos <george.lolos@uregina.ca>, halld-cal@jlab.org,
>> Eugene Chudakov <gen@jlab.org>, "zisis@uregina.ca"
>> <zisis@uregina.ca>
>> Subject: Re: cost estimates - more questions
>>
>>
>> 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
>> -
>> > > +=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+
>> > >
>> > >
>> >
>> >
>> >
>>
>>
>
> ( `,_' )+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=
> ) `\ -
> / '. | +
> | `, 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 -
> +=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+=-+
>
>