Physics Requirements Current CDC Design R&D Items What We Have Achieved (Publications) What is Left Out? Summary and Conclusions JLC CDC R&D Status As of May 2003

Introduction

Recoil Mass Resolution Jet Invariant Mass Resolution Good track cluster matching 2-track separation better than Time Stamping Capability Physics Requirements ? <10% hit loss at inner most layer for 250 GeV W’s

2T Design Current CDC Design 5 sense wires/cell x 14k cells ~100k field wires

Can we control gravitational and electrostatic wire sags for a 4.6m-long wires? Can we achieve a spatial resolution of 85 microns everywhere in this big chamber? Can we achieve 2-track separation better than 2mm? Can we stably operate 4.6m-long stereo cells? Is Lorentz angle small enough to allow straight cells? Is gas gain saturation observed for cools gas mixtures no problem? Is tension drop controlable for Al wires? How well can we time-stamp bunches? Is neutron BG no problem? (~3k hits/train for B=2T) R&D Items Proof of Principle Phase

Current Status of Hardware R&D

Gravitational and Electrostatic Sags (4.6m Test Chamber): NIM A383 (96) 391 Wire Tension Measurement: Report by Kato-san Cosmic Ray Tests (4.6m Test Chamber): NIM A441 (00) 393 Effects of Oxygen Contamination: NIM ??? 2-Track Separation (Baby Chamber + Beam): Draft 0 Lorentz Angle Measurement: NIM A479 (02) 278 Designing of Stereo-Wire Geometry for a Long CDC: NIM A428 (99) 403 Gas Gain Measurement: NIM A447 (00) 459 dE/dx Measurement: Draft final-1 Geant4-based Full Simulator: Hoshina-san’s D.Thesis Time Stamping: --> Hoshina-san What We Have Achieved

Mechanical Stability

Wire Sags NIM A383 (96) 391

Gravitational Sag Measurement Principle Electrostatic Sag H.V. offH.V. on Rotate & measure Compare &

Results Field WiresSense Wires

Wire Tension Drop Mar Jan Jul Dec Apr Sep %/year 10% drop/year 5%drop/year 9 years Field wire tension still keeps dropping! No tension drop for sense wires Used Al wires are not appropriate for CDC

Gravitational and electrostatic wire sag: predictable with reasonable accuracy Wire tension drop for Al field wires: unacceptable Need better wire material Fall back solution = e.g. Cu/Be but with a thicker endplates Mechanical Stability Summary

Spatial Resolution

Cosmic Ray Tests NIM A441 (00) 393

Results Deteriaration Oxygen Effect? Angle Dep.?

Oxygen Contamination NIM ???

Results

Results : Oxygen Concentration v.s. Resolution

Rapid resolution degradation with drift distance observed for the 4.6m chamber can be attributed to Oxygen contamination Average spatial resolution of 90 microns is possible This requires, however, sufficiently low Oxygen contamination Spatial Resolution Summary

2-Track Separation

Up stream Down stream Typical 2-Track Event (Tanashi: Normal Incidence) Very successful case 500nsec ~ 3.5mm It looks possible to separate 2 tracks as close as 1mm to each other!

Results : Tanashi Efficiency Spatial Resolution Normal Incidence

2-track separation of 2mm or better seems possible for normal incidence Slight degradation of spatial resolution observed for the 2nd hit whose effect may be estimated by MC simulation 2-Track Separation Summary

Lorentz Angle

NIM A479 (02) 278 Nuclear Instruments and Methods in Physics Research A 479 (2002) 278 ｡ V293 Lorentz angle measurement for CO 2 / isobutane gas mixtures K. Hoshinaa, K. Fujiib, *, N. Khalatyanc, O. Nitoha, H. Okunob, Y. Katod, M. Kobayashib, Y. Kuriharab, H. Kuroiwaa, Y. Nakamuraa, K. Sakiedaa, Y. Suzukia, T. Watanabee Tokyo University of Agriculture and Technology, Tokyo , Japan bHigh Energy Accelerator Research Organization(KEK), 1-1 Oho, Ibaraki-Ken, Tsukuba , Japan c Institute of Applied Physics, University of Tsukuba, Tsukuba , Japan d Kinki University, Osaka , Japan eKogakuin University, Tokyo , Japan Received 6 December 2000; accepted 21 January 2001 Abstract We have developed a Lorentz angle measurement system for cool gas mixtures in the course of our R&D for a proposed JLC central drift chamber (JLC-CDC). The measurement system is characterized by the use of two laser beams to produce primary electrons and ･ ash ADCs to read their signals simultaneously. With this new system, we have measured Lorentz angles for CO2/isobutane gas mixtures with di ･ erent proportions (95 : 5, 90 :10, and 85 : 15), varying drift ･ eld from 0.6 to 2:0 kV=cm and magnetic ･ eld up to 1:5 T: The results of the measurement are in good agreement with GARFIELD/MAGBOLTZ simulations. r 2002 Elsevier Science B.V. All rights reserved. Keywords : Lorentz angle ; CO 2/ isobutane ; Drift chamber ; JLC

Measurement Principle

Results Lorentz angles for various E, B, and Mixing Ratios B dependence

Measured Lorentz angles are well reproduced by Garfield/MagBoltz calculations Measured magnetic deflection coefficient is consistent with unity, justifying extrapolation to higher magnetic field The current cell design is OK for 2T operation Lorentz Angle Summary

Operational Stability

Stereo-Wire Geometry NIM A428 (99) 403

Shrink Factor How does this affect gas gain and operational stability?

Gain Stability Along Wires Gain variation < 25% (4.6m)

Stereo Wire Geometry Summary Design procedure (how to decide stereo angles and layer-to-layer spacing, etc.) for stereo wire geometry has been worked out Gain variation along stereo wires due to cell shrinking is at worst 25% for 2T (4.6m) design and is tolerable

Gas Gain Measurement NIM A447 (00) 459

Results 2.2kV2.5kV 2.6kV 2.7kV2.8kV 2.9kV 3rd peak?

CO2/isobutane is very special in the sense that its gas gain starts saturating at relatively low HV Good news for neutron BG Bad news for dE/dx measurements? Gas Gain Summary

dE/dx Measurements

dE/dx Measurement Draft final-1?

dE/dx Curve Results Average Pulse Shape proton pi electron Slight Saturation Effects

Results : Expected Particle ID Performance 80 sampling points 1GeV

Saturation effects are indeed there Despite the saturation effects, dE/dx as measured as a signal charge seems to carry useful information for particle identification How well we can use this information under a jetty environment is, however, an open question dE/dx Summary

3T Design

wire spacing, if we keep the same cell structure spatial resolution / wire Inner radius constrained by support tube Impossible/difficult to scale Then what happens to chamber performance? ^^ ) - - ) ^^ ) - - ) - - ) - - )

Momentum Resolution : Analytic Estimate 2T Design

3T Design We need more accurate estimation!

Aiming at Conceptual Design for 3T Option Based on Full Detector Simulation Current Status of Software R&D

Jupiter, Satellites, and Uranus K.Hoshina’s D-Thesis

Basic Software Design

Current Status of Jupiter (3T) Super Conducting Solenoid (SOL) Calorimeter (HCAL) Central Tracker (CDC) Intermediate Tracker (IT) Vertex Detector (VTX) Calorimeter (ECAL)

Momentum Resolution (3T) O(10) x worse than naively expected!

ZH events at Ecm = 350 GeV 2-Track Separation (3T) 2-hit separation = 2mm 2-hit separation = Tanashi data ~10% loss at the innermost layer

Time Stamping --> Hoshina

Framework (base classes) completed IR/VTX/IT/CDC/CAL/SOL implemented Baby Chamber simulator created, baby chamber performance data being fed back to Jupiter (Kuborie+Nakashi) Major remaining problems: momentum resolution time stamping capability Jupiter, Satellites, and Uranus Summary

What is Left Out?

Oxygen (Accepted but needs revision) dE/dx (Draft final-1?) 2-track (Draft 1) Time stamping (Draft 0?) Further studies on space charge effects Bulk space charge (Draft 0?) Local space charge (Nitoh-san?) Tension drop (Draft 0?) Diffusion (Nitoh-san?) Planned Publications On-Going Project

Proof of principle phase BG studies with Jupiter Tension drop problem (OK for 3T option) Engineering Design Phase Charge division Prototype chamber w/ stereo layers Readout electronics DAQ Remaining R&D Items

Summary and Conclusions

Can we control gravitational and electrostatic wire sags for a 4.6m-long wires? Can we achieve a spatial resolution of 85 microns everywhere in this big chamber? Can we achieve 2-track separation better than 2mm? Can we stably operate 4.6m-long stereo cells? Is Lorentz angle small enough to allow straight cells? Is gas gain saturation observed for cools gas mixtures no problem? Is tension drop controlable for Al wires? How well can we time-stamp bunches? Is neutron BG no problem? (~3k hits/train for B=2T) R&D Items Proof of Principle Phase yes No problem OK for 3T Hoshina-san ???

Most of R&D questions in Proof of Principle phase have been answered affirmatively! This means that original R&D goals are basically achieved We need to finish writing up papers as soon as possible! Next phase is engineering design, which requires a full scale prototype test We need to decide whether we enter that phase or seek for other possibilities Conclusions