Hrachya,
My idea on the segmentation was that when you are designing two arms of
a coincidence hodoscope, the best segmentation for a given number of
scintillators is obtained when the left and right arms have the same
number of counters. For example, here is a comparison between the
current design with 24 + 7 counter and a counter-example with 16+15
counters. I contrast these two in the first two columns below, only
to show that the statement from the PS design note, v9.1 "This
spectrometer design provides uniform acceptance over the energy range
of 12.4 GeV to 6.4 GeV using a minimum number of counters and readout
channels." is not fully optimized. I claim that a 16 + 16 design (see
the last column below) gives nice round numbers in terms of the energy
binning of the channels, does substantially better than the initial
segmentation scheme in terms of energy bin width, and still fits nicely
with the original electronics estimate of 32 counters.
Richard Jones
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24 + 7 design
|
16 + 15 design
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16 + 16 design
|
FS counter width
|
41.7 MeV
|
26.9 MeV
|
25 MeV
|
WS counter width (*)
|
20.8 MeV
|
20.8 MeV
|
20.8 MeV
|
FS counter energy span
|
1000 MeV
|
430 MeV
|
400 MeV
|
WS counter spacing
|
1000 MeV
|
430 MeV
|
400 MeV
|
minimum WS energy
|
3250 MeV
|
3000 MeV
|
3000 MeV
|
maximum WS energy
|
8250 MeV
|
9000 MeV
|
9000 MeV
|
minimum FS energy
|
3000 MeV
|
3000 MeV
|
3000 MeV
|
maximum FS energy
|
4000 MeV
|
3430 MeV
|
3400 MeV
|
minimum gamma energy
|
6250 MeV
|
6000 MeV
|
6000 MeV
|
maximum gamma energy
|
12250 MeV
|
12400 MeV
|
12400 MeV
|
gamma channel width
|
41.7 MeV
|
26.9 MeV
|
25 MeV
|
(*) The width of the WS counters is determined by more qualitative
criteria, as described in the PS design note. It does not affect the
segmentation, but does determine the effective overlap exists between
adjacent gamma energy channels. I just adopted the value from the
initial design for these alternate segmentation schemes.
Richard Jones
Hrachya.Hakobyan wrote:
Richard,
Let to answer to your last comments. I've attached the doc file
corrected:
I've put your comments into the text exept few comments requiring or
discussion or additional work. I left 7 points for my answers.
1.Polarimetry layout. I think we should not discuss the subject of Si
microstrips location. I'm not ready at moment to discuss the
optimisation of polarymetry configuration. I may compare 1 or 2 m
configuration of strips location out od magnet. The vacuum chamber is
currently at least 3.5m long. If enginners may evaluate it and confirm
feasibility of construction and installation of 4.5m long one, one may
move back all detectors and increase overall resolution. If the
widening of vacuum chamber at the exir is also feasible without extra
effotes, one may use the BNL magnet with 0.6m wide pole's width,
increasing the photon
energy range regidtered to lower energies... Thos kind of discussions
with engineers are important and necessarily part of the proposal
preparation.
2.I was trying to improve the sentence on " saturated field".
You may do it better... Franky speaking I never cared with mapping
problem(there is enough time!) but mostly was worried by need to
avoid extra expences.
3.Section Error! and its repeat is a result of .doc to .pdf
conversion, it is missing in .doc format.
4, Optimisation of PS layout is introduced by Jim and I agreed with his
sentence in the sence of the reasonable balance between the detector
granularity and an influence of smearing factors to reach a finest
photon energy resolution.
5. Showereing problem is more prononced from my knowledge as a
conversion in collimator walls,contributiong to low energy part of
bremmstrahlung. The task is to evaluate this contribution.
6.The choice of photon energy resolution as a half of FSF bin size and
smearing influence of beam spot size and multiple scattering is a part
of the balance mentioned in point4. If the vacuum chamber is ptolonged,
counters shifted back and the influence of smearing would be less...
7. I rewrite the definition of efficiency. please have a look.
Richard, we agreed to talk at your 10:00am. I'll ready.
Hrachya
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