MECO Requirements

1
MECO Requirements Parameters

• NSF RSVP Baseline Review
• Brookhaven National Lab
• April 20, 2005
• Michael Hebert

2
MECO Beam Requirements

• Beam momentum 7.5 GeV/c
• Two bunches in the AGS at 180? (? 1.35 ?s) with
  20 Tp each
• Beam slow extracted over 0.5 s in lt 50 ns wide
  bunches with a 1.0 s cycle
  time
• Inter-bunch extinction ratio, 1109 or better
• Narrow focus (sradius ?1 mm) beam on a small
  cross-section target with minimal material around
  it
• Flexibility in the steering to allow for beam on
  target with MECO solenoids in either polarity
• At a minimum 4 1020 protons delivered, reaching
  design sensitivity could require 50 more

3
1.3.1 Extinction

• Requirements
• lt 10-9 overall extinction from the combined
  effort of AGS Internal (in AGS WBS) and RF
  Modulated Magnet inter-bunch cleaning efforts.
• RFMM Design Parameters
• Six 1 m long modules
• 740kHz operating frequency (2 modules) two
  harmonics (2 modules each)
• 12 MeV total kick for filled buckets with respect
  to unfilled (2 mrad for 8 GeV p)
• 75 Gauss peak field
• 6 kW total power consumption
• Extinction Monitors one near RFMM, other in p
  beamstop
• Two 1 cm aperture spectrometers sampling a 10
  momentum range of protons scattering out of beam
  from a flag or the production target
• Small fixed field magnets out of existing
  inventory
• TOF counters with 100 ps resolution, equivalent
  to 20 momentum resolution
• Small scintillator-based calorimeter with 35
  resolution
• Detects extinction gt 10-9 in 100 s of integration
• For additional details see Reference Design Doc
  (MECO-EXT-05-001)

4
1.3.2 Target Shield

• Production Target (MECO-TGT-03-001)
• Requirements
• Minimum material around target to maximize p flux
• Handle 5 kW average power (10 kW peak) heat load
• 16 cm long, 6 mm dia. Au target rod, surrounded
  by 0.3 mm thick water layer and 0.5 mm titanium
  water jacket
• MECO Detector costs are for design and
  prototyping only
• Heat Shield (MECO-TGT-02-001)
• Requirements Limit heat and radiation load on
  PS coils
• 55 metric tons of copper, 21 tons of tungsten,
  supported by PS cryostat
• Water cooled at the OD, 16 kW average heat load
  to extract
• Expected performance
• Heat load on PS cold mass 91 W
• Maximum 21 ?W/g local energy deposition in
  superconductor
• 32 Mrad integrated dose to PS coils

5
1.3.3 Muon Beamline

• Vacuum System (MECO-MUB-03-003)
• 10-4 Torr in each of two separate systems, one
  for PS and TSu, one for TSd and DS
• 3 cryopumps, 2 turbopumps, gate valves, roughing
  pumps
• Control system to limit Dp across pbar window to
  8 psi during pumpdown
• Collimators and TS Shielding (MECO-MUB-03-002)
• Four collimators, 3 copper _at_ 1000 kg, 1
  polyethylene in TS to filter m beam
• Additional copper shielding in TSu to protect
  cold mass from rad load
• Pbar Absorbing Window (MECO-MUB-03-001)
• 0.58 mm thick, 50 cm dia. Kapton window
• Replaceable module in warm gap between TSu and
  TSd cryostats
• Neutron Absorbers (MECO-MUB-03-005,
  MECO-MUB-05-003)
• Several tons of polyethylene in and around the DS
  to limit neutron rates
• Muon Beam Stop (MECO-MUB-03-004)
• 3 tons of polyethylene, lead, and stainless steel
  to absorb muons that do not stop in the target
  foils

6
1.3.4 Tracker

• Requirements
• 900 keV FWHM energy resolution and no high E
  tails
• Minimum material to limit multiple scattering
• Operation in vacuum
• High rate handling capability
• Design
• 13000 5 mm dia. straws arranged in 54 modules
• 15 or 25 mm straw wall thickness
• Single ended readout, 13000 channels
• Digitizer is reworked BaBar Elefant ASIC
  providing TDC and ADC information, 8 channels per
  chip
• Additional Details in MECO-TRK-05-001

7
1.3.5 Calorimeter

• Requirements
• 7 MeV energy resolution
• 1.5 cm shower impact position
• Design
• 1024 (3.753.7512.0 cm) PbWO4 crystals arranged
  in four vanes of 256 crystals each
• Carbon composite support structure
• Each crystal is equipped with two large area
  Avalanche Photo-Diodes, 2048 total channels
• Both the front end electronics and the crystals
  are cooled to -24 C
• Readout electronics is in DAQ WBS
• Additional Details in MECO-CAL-05-001

8
1.3.6 Cosmic Ray Shield

• Requirements
• Single layer inefficiency of 1
• Three scintillator layers to reject neutron
  interactions
• Design
• Profile similar to MINOS, 10cm wide, 4.6m long
  slats
• 3120 scintillator slats total, 14 km of
  scintillator
• 3 WLS fibers per slat, 44 km of WLS total
• 104 multi-anode PMTs, 1560 total channels
• Readout electronics is included in Trigger and
  DAQ
• Additional details in MECO-CRS-05-001

9
1.3.7 Trigger and DAQ

• Requirements
• Digitize the Calorimeter and Cosmic Ray Shield
  signals
• Provide level 1 trigger from Calorimeter tower
  energies
• Provide higher level processing
• Handle status monitoring and slow control for all
  MECO Detectors
• Design
• 80 custom Calorimeter Digitizer Modules (CDMs)
• 75 custom Cosmic Ray Shield Digitizer Modules,
  possibly the same as the CDMs with different
  firmware
• Custom Event Builders
• Clock Distribution System
• 11 Custom Backplanes
• 4 to 8 Data Servers
• 56 processor CPU farm
• Additional details in MECO-DAQ-05-001

10
1.3.8 Simulation and Offline

• Requirements
• Provide detailed simulation of the detector and
  beamline
• Handle reconstruction of event data (200 Hz L3
  rate) with fast turnaround time
• lt 1 year to reconstruct entire dataset of 2109
  triggers
• Provide higher-level monitoring of detector
  systems in real time through prompt
  reconstruction
• Design
• Hardware
• Multi-CPU farm for event processing
• Data storage in tape silo (e.g. PDSF _at_ NERSC)
• Disk arrays enough to hold 25 of raw data and
  full DST set
• Most of hardware in operating budget MRE
  supports CPUs, disk, and tape for simulations,
  equivalent to 1 year of operations
• Software
• Flexible C based framework based on
  BaBar/CDF/E158 code
• Multi-level simulation, including physics
  processes, background mixing, detector hits and
  digitization, trigger acceptance
• Modular reconstruction