Calorimeter Upgrade

1
Calorimeter Upgrade
Gregorio Bernardi on behalf of
the Dzero Collaboration

• The Tevatron and Dzero Upgrades
• From Run I to Run II, in brief
• Preshower Detectors
• CPS design, status...
• FPS ...expected performances
• Calorimeter Electronics
• Constraints at Run II
• System Description
• Intercryostat Detector
• Objectives and status

2
Timings

• Bunch structure

gap used to form trigger and sample baselines
3.56us
Run I 6x6
superbunch
gap
4.36us
2.64us
396ns
Run II 36x36
this gap is too small to form trigger and
sample baseline

• We expect the bunch structure to evolve to a
  minimum 132 ns between bunches - design to that
• We expect 3 gaps, gap size must be a multiple of
  132ns (7 RF buckets)

3
Experiment

• Physics program at Run II (driven by high pT
  physics)
• Searches for phenomena beyond the SM
• Top quark studies
• Electroweak measurements
• QCD tests
• B physics
• Accelerator environment implies
• Fast electronics, pipeline
• Sophisticated trigger systems
• Radiation hard detector components

4
E.M. Calibration

• Use J/Psi , Upsilon , Z

5
DÆ Upgrade
6
Tracking System
Fiber Tracker
Silicon Microstrip Tracker
Forward Preshower
Solenoid
Central Preshower
7
Central Preshower

• Central Preshower already mounted on the
  solenoid
• Scintillator Lead
• Performances studied with MC and cosmic rays

8
Central Preshower

• Simulation results
• Good spatial resolution
• Preshower recovers resolution.

9
Forward Preshower

• Azimuthal wedges (u,v) scintillator/lead with
• readout via fibers

side view
10
Fwd Preshower

• Azimuthal Wedges ready
• Test beam results

11
Fwd Preshower

• Test Beam Results (FNAL 97)

12
Calorimeter Electronics

• Objectives
• Accommodate reduced minimum bunch spacing from
  3.5 us to 396 or 132 ns
• Storage of analog signal for 4us for L1 trigger
  formation
• Generate trigger signals for calorimeter L1
  trigger
• Maintain present level of noise performance and
  pile-up performance
• Means
• Replace preamplifiers
• Replace shapers
• Add analog storage
• Replace Calibration System

13
Calorimeter Electronics
SCA analog delay gt4usec, alternate
new low noise preamp driver
Trig. sum
Bank 0
SCA (48 deep)
SCA (48 deep)
x1
Filter/ Shaper
Preamp/ Driver
Output Buffer
BLS
SCA
Detc.
x8
SCA (48 deep)
SCA (48 deep)
Bank 1
Additional buffering for L2 L3
Replace cables for impedance match
Shorter shaping 400ns

• 55K readout channels
• Replacement of Preamps, Shapers, BLS, addition of
  SCA, new calibration.

14
Preamplifier

• similar to previous version except
• Dual FET frontend
• Compensation for detector capacitance
• Faster recovery time

New output driver for terminated signal
transmission
15
SCA

• Not designed for simultaneous read and write
  operations
• two SCA banks alternate reading and writing
• approximately deadtimeless to L1 rate up to
  100kHz
• Only 12 bit dynamic range
• low and high gain path for each readout channel
  (X8/X1)
• maintain 15 bit dynamic range

16
Calorimeter Electronics Upgrades

• Cables from cryostat to preamps
• replace 110 ohm cables with impedance matched 30
  ohm cables to minimize sensitivity to reflection
  
• Preamp motherboards
• 48 preamp hybrids per motherboard -- for improved
  high frequency performance
• BLS motherboards/ Crate Controller
• 48 BLS hybrids/motherboard to accomodate new SCA
  and shaper
• New/additional controlscoordinating the 144
  analog samples per channel
• Power Supplies
• use low noise commercial supplies
• power requirements increased
• New Calibration System
• accommodate timing constraints and have same
  or better precision.

17
Noise Contributions

• Reoptimized three contributions
• Electronics noise
• increases due to shorter shaping times
  (2 microsnds to 400 ns)
  (as sqrt(t))
• decrease due to lower noise preamp
  (2 FET input)
  (as 1/sqrt(2))
• Uranium noise
• decrease due to shorter shaping times (as
  sqrt(t) )
• Pile-up noise
• increase due to luminosity
  (as sqrt(L))
• decrease due to shorter shaping times
  (as sqrt(t))

18
Expected Noise

• Design for
• 400 ns shaping
• lower noise -- 2 FET input
• luminosity of 2x1032
• Which leads to
• electronic noise increase of 1.6
• uranium noise decrease of 2.3
• pile-up noise increases by 1.3
• comparable noise performance at 1032 with new
  electronics as with old electronics at 1031
• Pile-up effect on physics ?
• The W mass benchmark has been simulated and
  confirms that pile-up will not limit our W mass
  at Run II.

19
Intercryostat Detector (ICD)

• Objectives
• Maintain ICD performance in presence of a
  magnetic field and additional material from
  solenoid
• Improve coverage for the region 1.1ltetalt1.4
• Design
• A scintillator based Intercryostat Detector (ICD)
  with phototube readout similar to Run I design
• Expected Physics output
• Provides improvement to jet energies and missing
  energy in the region between the central and end
  cryostats

20
ICD Design

• Detectors
• 16 super-tiles per end with total of 384
  scintillator tiles covering 1.1ltetalt1.4
• WLS fiber readout of scintillator tiles.
  Re-use existing PMTs
• Clear fiber light piping to region of low field
• Calibration scheme as for L.Ar calo. But with
  adapted pulse

21
Conclusions

• Dzero is upgrading its detector
• L.Argon calorimeter untouched
• Harder machine conditions and new environment
  (solenoid)
• New Calorimeter Electronics
• Improved ICD
• New Central and Forward Preshower
• Similar Performances
• Detectors close to be ready to start
  taking data in Summer 2000