学術創成会議 一般報告 東北大学 山本均 , ILC 測定器学術創成会議

Change Controls ■ 14mrad+14mrad crossing angle IRs (one experimental hall) ■ CMS style detector assembly ■ Muon spoiler ■ Push-pull ■ Number of bunches → 1/2 測定器に直接かかわるもの：

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 ■ 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 CFS- conventional 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 ■ 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 ■ 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 ■ 当初の Luminostity →1/2 ■ コスト削減〜３％ ■ ‘Upgrade’ ◆ Low-p parameter set → もとの Luminosity Beam background が大きくなる ◆ RF を予定の数入れる → もとの Luminosity 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 NominalLow-P Nb2 E10 σx/y (nm)543/5.7452/3.8 σz (μm) Dy δBS2.2%5.7% Same luminosity

Pair background and Low-P ■ Very naively, ◆ Background on a given event (assuming bunch id) determined by hits per bunch crossing ◆ So, 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 Nominal Low-P

Low-P Pair background 500 GeV1 TeV K. Buesser, T. Maruyama, W. Kozanecki, etc.

Parameter committee ■ Scope document の見直し ◆ 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 ◆ 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