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[lcdds 119] Minutes of the fifth meeting for the IR task force, 8/10

Subject:   [lcdds 119] Minutes of the fifth meeting for the IR task force, 8/10
From:   "T.Tauchi" <toshiaki.tauchi@xxxxxx>
Date:   Thu, 11 Aug 2005 11:50:32 +0900

Dear Colleagues;

Can you find a minute of the fifth meeting for the IR task force ?
We welcome your comment and suggestion.

The next meeting will be in Septemvber, 1:30pm-3pm, 3gokan 425 and TV
conference with 31100.

Our homepage is http://acfahep.kek.jp/subg/ir/bds/mdi/IR.task.force.htm .

Best wishes,
Toshiaki Tauchi


Minutes of the fifth meeting for the IR task force
    •     Date and time: 3rd August, 14:00-15:00
    •     Place: 3-gokan, 425, KEK
    •     TV conference (ID=31100)
 Participants: T.Tauchi, Y.Sugimoto, A.Miyamoto (KEK), Abe (Tohoku univ.),
Matsunaga (Tsukuba univ.)

We discussed on the present status of the task force studies and the
WWS/urgent questions.

1. B and Machine-option dependence of RVTX, by Y.Sugimoto
 ( transparencies, pdf, 7 pages, 1MB )

Sugimoto calculated the well-defined beam pipe geometries with various
conditions, which are B-fields of 3,4 and 5T, and the nominal and high
luminosity parameter sets including the new ones at Ecm=1TeV(A.Seryi's). The
criterion is that the pair-background core should not hit the beam pipe,
where the core can be defined as the outermost edge with a steep slop of
greater than 10/0.5mm (particles/R) in radially projected distribution of
pair-particles as a function of z (along the beam line).

 The beam pipe should be apart from the core with 2mm and 5mm at z < 2.5m
and z=3.5m, respectively, where there are a straight Be pipe and cone-shaped
Al pipe at z< 2.5m. The innermost length of VTX-ladder is defined to be |cos
θ|=0.95 +2mm (Si-sensor) + 15mm (ladder). The first ladder should be apart
from the core with 2mm at least.

The B-dependence was shown with the 500GeV nominal parameter sets. The
500GeV high luminosity parameter set was compared with the nominal one.
Also, the new high luminosity parameter sets were compared with the 1TeV
high luminosity one. The radii of Be beam pipe (VTX innermost layer) vary
from 12.5 (16.6) to 9.5 (13.2) mm in B=3 to 5T, respectively, with the
nominal set. This radius vary from 18.5 (24.1) to 14 (18.4) mm in B=3 to 5
T, respectively, with the 500GeV high luminosity set. In the cases of 1TeV
high luminosity sets, the new set of High L'' can significantly reduce these
radii from 20.5 (25.8) to 13.5 (17.8) mm .

Finally, he concluded ; (1) Minimum radius of the vertex detector has been
calculated based on a consideration of direct pair background hits on beam
pipe (Other factors such as backscattering from BCAL should also be taken
into account for the actual design); (2) RVTX has a weak B dependence of
B-1/2; RVTX has a strong dependence on machine parameter set ; (3) Andrei’s
new parameters for High Luminosity option are very preferable from the
viewpoint of background. His approach should also be applied to 500 GeV case
if possible.

2. Background simulations based on LCBDS and Jupiter, by A.Sugiyama
 ( transparencies, LCBDS : pdf, 9 pages, 106KB, and  Jupiter : pdf, 2 pages,
44KB )

 First, Sugiyama explained what has been done for the LCBDS, whose slides
could not be shown at the previous meeting. The BDS optical elements (20mrad
crossing angle) have been installed in the LCBDS. The first results were
obtained with a Gaussian beam for check-out the basic performance. As shown
in figures, the beam is focussed as expected, while the input beam parameter
looks like that of warm machine(i.e. GLC). Increasing the beam sizes by 50
and 200 times in x and y directions, respectively, muons were generated in
the BDS. With limited statistics of 2,000 initial particles, 163 muons were
generated with 100 times MuonProductionFactor, while no muon reached to IP.
Also, 10 to 20 neutrons were generated including the downstream beam line of
the IP. He will convert the MAD file of 20mrad crossing extraction line to
the SAD for input to LCBDS. Then, disrupted beam, beamstrahlung photons and
pairs, which are generated by CAIN, will be input to LCBDS for background

Next, He briefly showed the present status of CAIN/Jupiter simulation
studies. The incoherent pairs were simulated with limited number of 1,000
particles for a test run. The TPC signals (hits) were shown. He would like
to know origins of the hits in Jupiter; i.e. electrons or photons or
neutrons, while the origins are difficult to be identified in the present
version. Also, he pointed out that Jupiter simulation takes too much time in
order to study backgrounds under various conditions. So, we have to think
about an efficient method.

3. Immediate plans

(1) Background studies of synchrotron radiation, muons from LINAC-end to IP
by LCBDS, by A. Sugiyama
    ◦The beam parameter should be the ILC ones with flat halo whose rate is
assumed to be 0.1%. So, the beam profile has a Gaussian distribution under a
0.1% uniform one. At the collimator section, the particles in the halo will
interact with collimators to generate muons, where the total number of
hitting the collimator should be 0.1% of the beam intensity. Tunnel geometry
must be important for muons in addition to muon spoilers.
    ◦Interface between CAIN and LCBDS must be prepared for the extraction
simulation. So, he should contact to Abe (university of Tokyo) who develops
the LCBDS.
(2) Pair background simulation in VTX, IT and TPC by Jupiter, by A. Sugiyama
 If possible, the FCAL and BCAL will be sensitive detectors in Jupiter, At
present, they are thick materials for background studies.
(3) Updates of IR geometries based on the baseline parameters as well as
DID, anti-solenoid fields. by A.Miyamoto

4. The urgent questions by WWS
 The questions and replies will be updated in following home page.
The questions with replies and comments