From: Yasuo MIAKE <ymiake@sakura.cc.tsukuba.ac.jp>
Date: 2002.9.24 14:14:49 US/Eastern
To: "L.S.Zolin" <zolin@moonhe.jinr.ru>
Cc: Yasuo MIAKE <ymiake@sakura.cc.tsukuba.ac.jp>, highpt-ml
<phenix-highpt-l@bnl.gov>
Subject: Re: prototype preparation
Dear Prof. Zolin,
I am glad to hear from you. I am BNL now. I will be back to
Tsukuba by the end of this week and am planning to be Osaka for
PANIC02 on Monday and Tuesday next week. I need to come back
to Tsukuba at least on tuesday. Since I won't have enough time
at Tsukuba in this weekend, I may not be able to find the socket
assembly you requested. We might have to order to Hamamatsu.
We will send you via airmail later on.
I think we can discuss many issues of construction at PANIC02.
Parameters we need to fix are ;
1) size of the cell ; 12x 12 or 14 x 14 cm2
Considering R6233, 14 x 14 is much easier to handle.
Our calculation (need a final check) shows that
we will have 5 % of occupancy if the cell is 12 x 12 cm2
If this is correct, then 14 x 14 cm2 will be still 7%.
I think this is good number at this moment.
2) Index of aerogel
Although many of our measurements have been done at n=1.015,
best index in terms of PID at PHENIX is n=1.007 - 1.01.
My impression at this moment is that n=1.007 is a bit too small
and n=1.015 is too large. I am negotiating the company to
make n= ~1.01.
3) I do not understand why p.e. number you obtained is smaller by
75%. Have you calibrate the gain factor of the PMT by yourself?
Do you obtain smaller Npe with R6233 and also FEU-184?
4) I think 0.5 radiation length should be OK with EM-cal.
My understanding is that as far as the material is uniformly
distributed, then, it should be OK since it is similar to the
first lead plate of the Pb-Sc EM-cal.
5) I took a picture of the area yesterday. We have only 19 inches
space due to sluminum structure for TEC. All the material
should
be <48 cm thick. Installation of TOF and Aerogel together is
getting
very tight. Tof requres at least 15 cm thick.
Looking forward to seeing you at Osaka!
Regards,
Yasuo MIAKE
On 2002.9.24, at 01:25 PM, L.S.Zolin wrote:
Dear Prof. Y.Miake,
As you know we had the short (~20 hours) test run in July with
aerogel counters. We reproduced the integration sphere cell
and measured Npe-response with PMT R6233 and Goretex.
Results are close to that of KEK May test.
However our Npe is about 0.75 Npe(KEK). We suppose that
this difference due to sum of systematic errors of 1pe-calibrations
of read-out electronic in KEK and Dubna, or maybe PMT which we
used (R6233 marked as "A5") has a lower photocathode sensitivity
against PMT's used at May-test.
Now we bought PMT FEU-184 (3-inch) produced in Moscow and we plan
to perform comparative beam-test of R6233 and FEU184 at the next
run (the end of Oct.-beginning of Nov.).
Concerning cells preparation.
We hope to prepare one/two type cells discussed in KEK
both "integration sphere"-type.
As you noted a construction should be much similar to the final
version and two options should be observed:
compactness and low mass (minimum radiation length).
If we will use as box-material Al of 0.5mm thickness and
the assembly of R6233 we have the next estimation of
component contributions in 1 cell weight:
1) Box(Al) - 300g
2) PMT 6233 - 190g x2 (2 pieces)
3) Magnetic shield - 180g x2
4) Socket assembly - 156g x2
5) PMT-connector to - 170g x2
box (May-test like)
In summary: - 1700g per 12x12cm^2 of cell cross section
or 12g/cm^2 (0.5 rad. length of Al
- check, please, this estimation)
Is it admissible for the aerogel panels placed in front of
PHENIX EM-cal.?
In accordance with above estimation we suppose:
1. O.5mm Al is acceptable for cell construction ( or 1mm is also OK?)
2. Contribution (4) and (5) can be decreased in prototype
with use other constr. choices.
3. Is it necessary to use the magnetic shield ?
One of main point is the cell size.
In May test the aerogel slabs of 12x12cm^2 were used.
This size is difficult to conjugate with PMT R6233 assembly length.
In the draft of High Pt aerogel project the another size is
indicated, 14x14x10cm^3, - is it the final choice?
Please confirm this because it is a principal point at construction.
Best regards
A.Litvinenko
V.Peresedov
L.Zolin
P.S.
It seems, it would be desirable to have 2 socket-assemblies
of E6316-type (2 pieces) for preparation of prototype in Dubna,
or even if only 2 sockets from the assembly, because
we cannot to find in our Institute a socket to be compatible with
R6233.
(One of us, L.Z., will be probably at PANIC02 in Osaka and
it is opportunity to transfer the sockets for Dubna cell-preparation
if possible to support this request).
***********************************************
Yasuo MIAKE miake@tac.tsukuba.ac.jp
or miake@mac.com
Home Page http://utkhii.px.tsukuba.ac.jp/
Inst. of Physics, Tel;+81-298-53-4254
Univ. of Tsukuba Cell; 090-7406-6558
Tsukuba, Ibaraki 305-8571 Fax;+81-298-53-6618
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