学術創成会議
一般報告
東北大学 山本均
2006.9.27, ILC測定器学術創成会議
Change Controls
測定器に直接かかわるもの:
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14mrad+14mrad crossing angle IRs
(one experimental hall)
CMS style detector assembly
Muon spoiler
Push-pull
Number of bunches → 1/2
Tentative 14mrad x 2 design
Two 14mrad IRs
■
Class 2 CCR (charge control request)
◆ 最重要の変更項目
◆ CCB
(charge control request) のあとGDE ECが最終
判断
◆ 承認された→現在のbaseline
■
9月のMAC(machine advisory committee)で
GDEが物理コミュニティーとの連携の例と
して発表
Two 14mrad IRs
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■
■
■
■
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Vancouver06でGDEがBDS AGにCCRを提出
することを要請
BDS AG(私)が他のWWS co-chairsに即座
に連絡
その後すぐにMDI panel membersにも連絡
BDS AG がCCRをCCBに提出
CCBがWWSとMDI panel(ほかCFSconventional facility systemなどにも)にinput
を要請
WWSがMDI panelにinputを要請
BDS cost
Surface Detector Assembly
■
実験ホールを掘っている間に測定器の組み立て
が出来る。
◆
■
■
■
■
約2〜3年早まる。
CCR提出済みー CCBが検討中(WWSにinputを要
請)
Class-1 : <100M$ (GDE ECに行かない)
10月12、13日、山岡、田内、山本がCERN
訪問(+Wolfgang Lohmann, Phil Burrows etc.)
各測定器概念は具体的アセンブリ設計を検討中
◆
10月2日GLDアセンブリ会議
Surface assembly
Underground assembly
Muon spoiler
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■
従来:IRから数100mに厚さ9mと18mのトロイド
磁石/ビーム
CCR : 5mの磁石/ビーム
◆
◆
■
■
Muon rate ~ x40
9mと18mのspoilerのスペースは作る
Class-1
9月23日にCCBが承認
Muon Spoiler
Push-pull
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■
■
■
■
1 IR, 1 BDS, 2 detectors
コスト削減は大きい
おそらくClass-2 (GDE ECが最終決定)
CCR提出はValenciaあたり?
GDE(barry)が正式にWWS, MDI panel, parameter
committeeに検討を要請(昨日)
Reducing #bunches by 1/2
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■
■
当初のLuminostity →1/2
コスト削減〜3%
‘Upgrade’
◆
Low-p parameter set →もとのLuminosity

◆
RFを予定の数入れる→もとのLuminosity

■
Beam backgroundが大きくなる
Upgradeにかかる時間と費用?
GDE(barry)が正式にWWS, MDI panel, parameter
committeeに検討を要請(昨日)
To: WWS, MDI and Parameters Group
As you know, we are in the process of studying a variety of possible cost saving
options. As part of those exercises we are assessing the impacts as much as
possible, to decide with to submit for consideration as change requests. For a
couple of these options, we want to involve the physics community as early as
possible in the process. I attach two notes outlining two of the studies we are
initiating:
• "Reducing the number of bunches." (This change would have the feature of reducing
initial RF and therefore luminosity, but is totally recoverable when full luminosity is
needed) We want to work with the physics community on whether this early
reduction is tolerable from physics standpoint and how it might fit into an early
running plan.
• "Changing BDS to one beam line, one IR and push-pull system.“ We are initiating studies
(see the note) and want to include the physics community in these feasibility
studies. Perhaps a representative of each detector concept could participate directly
in the studies?
Let me emphasize that no decision has been made on either of these changes. But, we
now have assessed the costs of the baseline and have concluded that we
must substantially reduce costs. These and other studies will help us to determine
which of the cost saving options we will submit to the Change Control Board.. Please
work with your communities to begin the necessary dialogues and to determine who
should directly work with the GDE on these studies.
Thanks, Barry
Low-Parameters with 1/2 #bunches
Nominal
Low-P
Nb
2 E10
2 E10
σx/y (nm)
543/5.7
452/3.8
σz (μm)
300
200
Dy
18.5
27
δBS
2.2%
5.7%
Same luminosity
Pair background and Low-P
■
Very naively,
◆ Background
determined by hits per bunch crossing

◆ So,



■
on a given event (assuming bunch id)
if pairs ∝ luminosity,
Background hits ∝ bunch luminosity
Namely, Low-P background ≈ 2× nominal background
‘2×’ applies to all backgrounds proportional to luminosity
 Two-photon, radiative Bhabha, debris ...
For pairs, effects can be more than ×2
◆ Pt


of the pairs ∝ E field on the surface of bunch
Pt is ~1.5 times larger for Low-P than nominal
More pairs hits the detector
Low-P Pair background
Energy deposition on BEAMCAL
Stau search for 14 mrad with anti-DID
Nominal : ~40% lum. Loss for stau search
Low-P : ~ lum. loss of more than x2
Low-P
Nominal
Low-P Pair background
~ 26.3 hits mm
-2
/ SW (50 s)
VXD Hits mm-2 /train
500
Layer #1
400
500 GeV
1 TeV
300
200
Tol ( = 6 hits mm-2 / 50 s)
100
0
0
2
N
4
Q Y P H
500 GeV
6
N
8
Q
10
Y P H
1 TeV
K. Buesser, T. Maruyama, W. Kozanecki, etc.
Parameter committee
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Scope documentの見直し
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エネルギー、ルミノシティー、#IR etc.
議長:Rolf Heuer
物理working groupに質問を提出
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物理working groupを世界的に編成する必要有り
今回のparameter committeの要請には間に合わず
WWSはglobal coordinationを個々のWG leaderに要請
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