# Presentation: 621039

## The DØ Detector  for Run II

- Introduction
- Physics Motivation
- Accelerator Environment
- The DØ Upgrade
- Overview
- Elements of the Upgrade
- Physics Potential
- Conclusions

**Stefan Gr****ü****nendahl**
**Fermilab**

## Physics Goals

- Precision Tests of the Standard Model
-     Continuation of present DØ physics
-      program, with some shift  in emphasis
- precision measurements
-        (top mass, W mass, ...)
- Constrain the Higgs Boson Mass
- improvements to B physics capabilities
-     (Bs mixing, approach to CP violation, ...)
- QCD with W,Z, 
- Extend the Discovery Reach
-      Significant improvement to physics reach
- few fb-1 data samples allow significant increases in the reach for SUSY, leptoquarks, W’,Z’,anomalous couplings....
-  Extended luminosity  (5 - 25 fb -1): intermediate mass Higgs

## The Detector

- The DØ upgrade builds upon the strengths of the existing detector
-  (excellent calorimetry, muon coverage) and augments it with a
- high resolution Silicon/Scintillating Fiber tracker.

- calorimeter: replacement of preamps/shapers
- muon system:
- replacement of muon chamber readout electronics
- Iarocci drift tubes replace forward muon chambers
- central and forward scintillator pixel layers enhance trigger capability.
- DAQ & trigger: add buffering, add processing power
- central tracker:
- 2 T supraconducting coil inside r=70 cm calorimeter bore
- lead/scintillator preshower detector with fiber/VLPC readout
- 16 layer SciFi/VLPC tracker (80k channels)
- 4 barrel / 16 disk Silicon tracker (1M channels)
- forward tracker/preshower: scintillator cells with fiber/VLPC readout

## Tevatron Impact

- Impact on DØ
- Integrated *L *rad damage in tracking chambers replace
- Shorter bunch crossing interval avoidpileup   electronics pipeline
- Systems either Upgraded **Cal, Muon,Trig/DAQ **
**	****   ****	**or:                 Replaced **Tracking System**
- Solutions involve new Detector Technologies
- Silicon strip detectors, SciFi, trigger processors
-    The DØ Upgrade is designed to exploit unique opportunities offered by the Tevatron during Run II **and beyond**

## DØ Tracking

**DØ Tracking**

**calorimeter cryostat**

**1.1**

**1.7**

- 1.3 m

- 50 cm

- Solenoid
- 2T superconducting
- Fiber Tracker
- Eight layers sci-fi ribbon doublets               (x-u or x-v)
- 77,000  830 m fibers w/ VLPC readout
- Silicon Tracker
- Four layer barrels (double/single sided)
- Interspersed double sided disks
**800,000 channels**
- Preshowers
-    Central
** **Scintillator strips
-  6,000 channels
- Forward
-  Scintillator strips
-  16,000 channels

## Silicon Vertex Detector

**Characteristics**
- precision measurement of charged particle tracks with near interaction point
- size of luminous region: 25 cm
- hit resolution: 10 m
- impact parameter resolution:
- 40 m (xy), 100 m (z)
- mechanical alignment to < 25 m
- strip position known to < 5 m
- radiation hard to 1 Mrad
- operate at < 15O C
- about 800,000 channels
- < 1.5% bad channels
- AC coupled double/single sided detectors
**Geometry**
- 4 layers per barrel**     **
**1.  (r********,90****o****)****	**
**2.**** **** (r********,2****o****)   ****	**
**3.  (r********,90****o****)****	**
**4.  (r********,2****o****)****   ****	**

- additional
- disks (F & H)

- Disk/barrel modules

## Silicon Vertex Detector

- SVXII chip
- rad hard 1.2 m CMOS technology
- preamp/analog delay/ADC
- 128 channels
- 32 cell pipeline
- 53 MHz readout
- size: 6.2x9.7 mm
- 5 mW/channel
- chips are on hand
- High Density Interconnect (HDI)
- two layer fine pitch hybrid

## Fiber Tracker

**Fiber Tracker**

**Barrels**
**8 carbon fiber barrels**
**20<r<50cm**
**full coverage to********= 1.7**
**Scint Fibers**
******m ****Ø****, ****multiclad**
**2.6m active length**
**10m clear waveguide to photodetector**
**rad hard  (100 krad)                (10yr @ 20cm @10****32****)**
**Fiber Ribbons**
**8 axial doublets**
**8 stereo doublets        (2****o**** pitch)**
**Readout**
**77,000 channels**
**VLPC readout**
**run at low temp (9 K)**
**fast pickoff for trigger**
**SVXII readout**

**side view**

**end view**

## Fiber Tracker

**Visible Light Photon Counter (VLPC)**
**Avalanche  Photo Diode**
- well matched to light from fiber ( = 525 nm)
- quantum efficiency 
- fast response, high rate capability
- Si:As (band gap = 0.05 eV)
- high gain (, low gain dispersion
- operate at
-   8 K < T < 10 K,  6 V < Vbias< 7.5 V

## Specifications 
provide e trig (L1) & e-ID/-ID off-line
2X0 preradiator (solenoid + lead) & triangular strips (axial + 20o stereo u-v) with VLPC readout
light yield: 20 p.e./layer for min. ionizing measured
Central preshower, < 1.3
reduce e trig by 3-5
rad dose: 18 krad - ok

- provide e trig (L1) & e-ID/-ID off-line
- 2X0 preradiator (solenoid + lead) & triangular strips (axial + 20o stereo u-v) with VLPC readout
- light yield: 20 p.e./layer for min. ionizing measured
- Central preshower, < 1.3
- reduce e trig by 3-5
- rad dose: 18 krad - ok

**Central Preshower**

- position resolution
- (weighted) for  ;  < 1.4 mm for 10 GeV e

- 7680 Axial + stereo fibers in extruded triangular strip  (7 mm base width)

## Forward Preshower

- Specifications
- provide electron trigger in
-     1.4 < < 2.5
- uses same technology as central preshower (5mm strip base)
- provides factor 2-4 rejection for electron trigger

**2 x 8k ch, 2 sets of u-v  strips with lead in between**

## Tracker Performance

- Tracking
-   momentum resolution significantly enhanced
- secondary vertexing capability with silicon  tag b-quark decays
- sign determination for electrons
**triggering** using central tracking
- Preshowers
- enhanced e and photon ID (central & forward)
- forward e-triggering: additional x3-5 rejection

## Tracking Trigger

- Feed all axial fibers plus preshower into gate arrays
- Trigger if a fiber combination is consistent with PT > (1.5,3,6,8) GeV
- Tag categories (incl. CPS info): track, isolated track, electron, ...

- Trigger response for Z ee with 4 min.bias

## Muon System Upgrade

**Muon System Upgrade**

**Shielding**

**APHI Barrel Scintillator**

**Wide Angle **
**Muon PDt’s**

**Forward Trigger**
**Detectors**

**Forward Tracking**
**Detectors (MDT)**

## Muon System

- Wide Angle Muon Proportional Drift Tubes (PDT)
- use existing PDT’s for <1
- use faster gas (Ar-CF4-CH4) to decrease drift from 750 ns  450ns
- replace front-end electronics for deadtimeless operation
- Cosmic Ray Scintillator
- provides time info for  ID and tagging PDT hits in outer two layers
- add bottom layer to complete coverage
- A-PHI Barrel Scintillators
- time info and matching of  tracks to fiber tracker
- Forward Trigger Detectors
- Scintillator pixel counters provide time information and match  tracks in fiber tracker
- 3 layers to reduce combinatorics
- Forward Tracking Chambers
- mini-drift tubes provide hit info in 1< |< 2
- operated in proportional mode
- 3 layers provide independent muonmomentum measurement
- prototype tested in D0 run I (high rate)

## Trigger Architecture

**Trigger Architecture**

**L1 Trigger**

**L1**

**Global L2 Stage**

**L2 Preprocessors**

**Buffers**

**Silicon**

**Fibers**

**Preshw**

**Muon**

**Cal**

**p-bar**

**p**

**L3 **
**Processors**

**Trigger**
**Framework**

**10 kHz**

**1kHz**

**10-20Hz**

**tape**

**250kb/evt**

**L0**

## Trigger Schematic

## L1/L2 Trigger Configuration

- L2: Combines
- objects  into e, , j

- CAL

- FPS
- CPS

- CFT

- SC

- MDT

- PDT

- PS

- CAL

- CFT/
- CPS

- Muon

- L1: ET  towers, tracks
- consistent with e, , j

- Muon

- Global
-    L2

- Track

- PS

-   Cal
- e / j / Et

## Rate Simulations

- Background Event Sample
- Twenty-four ISAJET subsamples
- A total of 2, 4, 6, 8 overlayed interactions
- One selected from 2-5, 5-10, 10-20, 20-40, 40-80, 80-500 GeV Parton Pts
- Geant Simulation.
- Triggers Included:
- L2 Electron, Jet, Et, Tracks
- L1 CAL, CPS, PS, Muon
- Rate Calculation
**N = **number crossings w/ beam (5.1MHZ)
**fr****i**** = **fraction of crossings with I interactions
**p****ij**** ****= **fraction of events passing trigger with I interactions and a parton in the Jth bin.
******j**** = **cross section in Jth bin
****** ****= **j

## Trigger Example

_**Central Electrons:**_

- L1 Terms:
-     1 Central EM tower > 7 GeV
-                   plus
-     1 CFT track > 6 GeV/c
-          with Matching CPS
- L1 Rate 220 Hz

- L3 Terms:
-     ET > 20 GeV
-     Shape Cuts
- L3  = 0.01 b,  2 Hz

- L2 Terms:
-     ET > 7 GeV
-     Isolation, Shape Cuts
-     Match Cluster / Track
- L2  Rate 48 Hz

## Trigger Coverage and  Rates

- L1 Components:
- Central Fiber Tracker
-  **-1.7 < ******** < 1.7**
- Central PreShower
-  **-1.3< ******** < 1.3**
- Forward PreShower       **1.4<|********|< 2.5**
- CALorimeter
**-4.0 <******** < 4.0 (had)**
**-2.5 < ******** < 2.5 (EM)**
- MUON
**-2.0 < ******** < 2.0**

## DØUpgrade Performance

- Muon System
- lower thresholds: single muon pT > 8 GeV/c, dimuon pT > 3 GeV/c
- reduced backgrounds and triggering with additional shielding
- Calorimeter
- performance at 2x1032 comparable to present performance at 2x1031 (actually 17% worse)
- ability to calibrate in situ (E vs p available)
- Tracker + Preshower
- see above
- Triggering
- increase bandwidth:
- 10kHz L1 accepts,
- 800Hz L2 accepts,
- 10-20Hz to tape
-  more than an order of magnitude improvement over present system
- investigating possibility of Silicon vertex trigger

- Coverage
- Muons:  -2 < < 2
- Calorimeter:
- hadrons: -4<  < 4
- electrons/photons: -2.5 < < 2.5
- Silicon: -3 <  < 3
- Central Fiber Tracker: -1.7 <  < 1.7
- Central Preshower: -1.3 <  < 1.3
- Forward Preshower: 1.4 < |  | < 2.5

## Squark/Gluino Search

- use Missing pT + jets
- need good ETmiss resolution
- aim to run unprescaled ETmiss trigger in Run II (threshold studies)
-  Maximum reach in Run II 300 GeV

## Chargino/Neutralino

- Trilepton  + Missing pT
- low backgrounds
- Covers large fraction of SUSY parameter space
- need lepton acceptance =3 for pT>5 GeV/c

## Top squarks

- if m(stop) < m(top)
-                                                                                                                   detectable
- 	                                                                                                            at
- 		                                                                                                 Tevatron
- Single lepton channel
- Lepton+bjet+jets+Missing pT
- Mass reach for RunII (2fb-1)    150 GeV
- dilepton channel
- 2lepton+jets
- top squark mass reach  150 GeV (RunII)
- Missing pT + acollinear jets
- top squark mass reach in  RunII 150 GeV

## Higgs

- Needs very high luminosities
- samples of 10 - 30 fb-1
- Light Higgs search (80<mh<130 GeV)
- out of reach for LEP2
- difficult at LHC (accessible only via H)
- best hope at Tevatron qqbarWH, H  bb
- for MH=80 GeV, 10 fb-1 yields 60 events, and S/B=1/5.8 ...      more studies
- use jet-jet spectroscopy and b-tagging
- even more difficult: qqbar  H(W/Z) with H  tau+tau and (W/Z)  jj

## Higgs Trigger

**Higgs Trigger**

- Tracking trigger makes rates acceptable
- Demonstrates gain from **S**ilicon **T**rack **T**rigger

- Efficiency vs. Rate for CFT + CAL (no STT)

- STT improves Efficiency vs. Rejection

- STT+
- CFT+CAL

- CFT+
- CAL

## Conclusions

- The DØ detector for Run II builds on the strengths of the present DØ detector (calorimetry, hermeticity, coverage).
- Addition of high precision tracking system will enhance the physics capabilities.
- All systems are designed to run at high luminosity (1032) and reduced bunch spacing (132ns).
- Looking forward to exciting physics (discovery, precision measurements....).