# Presentation: 078071

## The Run II DØ CalorimeterElectronics Upgrade and its Performance

- Shaohua Fu
- Columbia University
*for the D**Ø Collaboration*
- 2003 IEEE Nuclear Science Symposium
- Portland, Oregon   October 19-25, 2003

## Tevatron Run II

- Successful Run I (1992-1996)
- Run II upgrade
- s : 1.8 TeV  1.96 TeV
- Luminosity plans to FY2009:
- 4.4 fb-1 (base) – 8.6 fb-1 (design)
- Run I delivered luminosity ~ 120 pb-1
- Bunch structure: smaller bunch crossing time

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

**Notes:**
The major upgrades include the construction of the Main Injector and the Antiproton Recycler, within a common tunnel.

## DØ Upgrade

- Upgrade Calorimeter readout electronics
- Silicon and Fiber tracker with 2T solenoid magnetic field for central tracking and momentum measurement
- Add Preshower detectors
- Add scintillator detector in muon system for faster trigger
- Pipelined 3-level trigger and new Data Acquisition system

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

**Notes:**
The Inter-cryostat Detector is on the inner surface of each End-cap Calorimeter cryostat.

## Calorimeter Overview

- Liquid argon sampling
- Stable, uniform response, rad. hard, fine spatial seg.
- L. Ar. purity important
- Uniform, hermetic with full coverage
- || < 4.2 (  2), int > 7.2 (total)
- Uranium absorber (Cu or Steel for coarse hadronic)
- Compensating e/ response, dense  compact
- Run I Energy Resolution (from test beam)
- e: (E/E)2 = (15%)2/E + (0.3%)2  (e.g. 3.4% @ 20 GeV)
- : (E/E)2 = (45%)2/E + (4.0%)2  (e.g. 11%  @ 20 GeV)

- ICD

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

**Notes:**
A calorimeter cell: G10 sheet laminated with copper pad is the signal board, with a positive potential of 2 kV. The uranium absorber plates are grounded. The gap in between is filled with liquid argon, where the electron drift time is 430 ns.
int – total nuclear absorption length. At  = 0, the CC has a total of 7.2 nuclear absorption lengths (A); at the smallest angle of the EC, the total is 10.3 A. Radiation hard.
e/ – the response ratio. The resolution and linearity obtainable in the calorimeter is closely related to the ratio of response of electrons and pions. Run I test beam results: the e/ response ratio falls from about 1.11 at 10 GeV to about 1.04 at 150 GeV.

## Intercryostat Detector (ICD)

- Objectives
- Improve coverage for the region 1.1 < || < 1.4
- Improve jet energy and missing energy
- Maintain the performance in the presence of a magnetic field and additional material
- Design
- Scintillator based with phototube readout similar to Run I design. Re-use existing PMT’s.
- 16 *supertile* modules per cryostat with a total of 378 scintillator tiles
- WLS fiber read out of scintillator tiles
- Clear fiber light piping to region of low field
- 	~ 40-50% signal loss over 5-6m fiber
- Readout/calibration scheme for electronics same as for L. Ar. Calorimeter but with adapted electronics and pulser shapes
- LED pulsers used for PMT calibration
- Relative yields measured > 20 p.e./m.i.p.

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

**Notes:**
PMT – photomultiplier tubes
WLS – wavelength shifting fibers
> 20 p.e./m.i.p. – The overall combination of scintillator, wavelength shifter and phototube gave approximately 20 photoelectrons per minimum ionizing particle for the crucial larger  boxes. Since the typical number of particles crossing a given tile in a typical high-pT 2-jet event is of order 25, the signals from the ICD are quite large.

## Upgrade of Calorimeter Readout

- Objectives and performance criteria
- Accommodate reduced minimum bunch spacing from 3.56 s to 396 ns
- Storage of analog signal for 4 s for L1 trigger formation
- Generate trigger signals for Calorimeter L1 trigger
- Maintain present level of noise and pile-up performance
- Update for 55,000 readout channels
- Replace signal cables from cryostat to preamps (110  30 for impedance match)
- Replace preamplifiers, shapers, baseline subtraction circuitry (BLS)
- Add analog storage (48-element deep Switched Capacitor Array (SCA))
- Replace timing and control system
- Replace calibration system (new calibration pulser + current cables)
- Keep Run I ADCs, crates and most cabling to minimize cost and time

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

**Notes:**
BLS: baseline subtractor
SCA: switch capacitor array
ADC: analog to digital converter

## Preamplifier

- New calorimeter preamp
- Hybrid on ceramic, 14 species + 1 for ICD
- 48 preamps on a motherboard
- New low-noise switching power supplies in steel box

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

**Notes:**
jFET – junction field effect transistor
Two input low-noise jFETs in parallel are used to compensate for the higher electronic thermal noise due to the shorter shaping time.
Fourteen (plus one for ICD) different species of preamplifiers are used to compensate for various capacitances of detector cells.

## BLS and SCA

- ADCs have 12-bit dynamic range. To achieve 15-bit dynamic range, SCAs have low and high gain path for each readout channel (8/1).
- SCAs are not designed for simultaneous read/write operations. Two banks of SCAs, upper and lower, for alternate read/write operations.
- No dead time for L1 trigger rate of 2-5 kHz.
- Readout tower of 0.10.1 in , trigger tower formation 0.20.2 in  for Level 1.

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

## Electronics Calibration System

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

**Notes:**
One unit of the calorimeter calibration system is composed of one pulser control board and its power supply, and six active Fanout boards housed inside of the preamplifier boxes.
The pulser control boards can set the amplitude and the delay of the calibration signal.
The switches on the Fanout convert the DC current to calibration pulse and send the calibration signal to the preamplifiers.

## Calorimeter Calibration (1)

- Online calibration
- Pulse shape measurements
- Liquid argon purity
- Reflection (impedance) measurements
- Timing corrections
- Debugging and noise studies
- Linearity measurements and corrections
- Offline calibration
- Data quality control
- Trigger performance
-  inter-calibration
- Absolute EM scale from* **W/Z*, *J/*** and ** events
- Electron ID, Jet ID and missing ET
- Energy flow jet algorithm – track-calorimeter combination
- Jet Energy Scale

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

**Notes:**
The linearity is verified by comparing the electronics response versus the pulse height for each gain path (8 and  1). We have measured excellent linearity for calorimeter energy deposits greater than 1 GeV. For smaller energies the non-linearity is corrected for all channels.
J/psi mass = 3.1 GeV, Upsilon mass = 9.46 GeV
To determine the Jet Energy Scale, we measured the calorimeter response to jet by using -jet events. The transverse energy of jet is compared to the calibrated energy of photon.

## Calorimeter Calibration (2)

**Calorimeter Calibration (2)**

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

## Physics Results

- Preliminary results using Run II DØ calorimeter data have been shown at conferences, including QCD, Electroweak, B, Higgs, Top and New Phenomena physics.
- Upgraded calorimeter performs well. We have about 200 pb-1 data.

*There are a lot more to come!*

- 2003 IEEE Conference, Oct 19-25

- Shaohua Fu  Columbia University

**Notes:**
The inclusive jet cross section as a function of jet transverse energy, with the measured values compared to the theoretical predictions of perturbative QCD in NLO.
Z cross section measurement in di-electron channel. The distribution of the invariant mass of the two electrons for Z candidates (QCD background has been subtracted). The Z mass peaks at 91 GeV, and the cross section is measured to be 275 pb.
To conclude, the upgraded calorimeter has been performing well in Run II. Now we have 200 pb-1 data, and there are more physics results to come.