MINERvA Director Review

1
MINERvA Director Review

• Optical Cables and Scintillator Extrusions

2
Active detector elements

• WLS (wavelength shifting) fibers in scintillator
• Extruded triangular scintillator pieces 3.3cm by
  1.7 cm
• ID - Active Target - triangular scintillators
  form a layer (128 triangles/layer)
• Light sharing between adjacent strips gives
  position measurement
• Extruded square scintillator pieces 1.9 cm
  square
• OD - Side hadron calorimeter - 6 layers

3
Active Detector Elements

• WLS fiber 1.2 mm, 175 ppm, s-35 multi-clad
  Kuraray fiber
• Same kind of fiber used CMS HCAL and CDF
  Preshower
• Slightly less flexible than the most flexible
  Kuraray fiber
• With attenuation length of more transparent fiber
• Readout one end mirror the other end
• Longest WLS fiber length 3.5 m
• Clear fiber in optical cables takes light to PMT
  box
• 1.2 mm s-35 Kuraray multi-clad fiber
• Length about 1.2 m OD -1.4 m ID

4
Active Detector Elements

• PMT Box
• Brings light from clear fiber cable to
  multi-channel PMT
• The piece which consists of the optical connector
  and clear fibers we call the ODU (optical
  decoder unit)
• Cable end connects to the clear cable
• Fiber end glued to PMT cookie

5
DDK Optical Connectors and Cables
Clip
Box
Ferrule

• 3 Parts Ferrule, box, and clip uses clip
  instead of pins and screws
• Designed by DDK (now Fujikura) in conjunction
  with the CDF Plug Upgrade
• RMS of light transmission - 1 to 2 (connection
  reconnection)
• For CDF holes for 0.83 mm, 0.9mm, and 1.0 mm
  fiber
• Also used by FOCUS, D0, and STAR experiments
• We will have DDK design new ferrule for 1.2 mm
  fiber same clip and box
• Optical Cables MSU STAR method to make light
  tight
• For light tight - RTV boot on both ends with
  black tube surrounding the fiber

6
Physics Requirements

• We require enough light to get a position
  resolution of 3 mm
• 8 pe/layer (photo-electron /layer) from Monte
  Carlo program
• Per doublet for a MIP with perpendicular
  incidence
• To determine particle type from dE/dx
• 8 pe/layer from Monte Carlo program
• The position and dE/dx determination should be
  measured directly rather than deriving them from
  the Monte Carlo program with the pe
• Less than a few mm of warping of scintillator in
  xy direction
• Need to know position of scintillators
• However, source scanning of layers will give this
  information

7
Vertical Slice Test I - pe

• pe is measured with VST I
• First triangular extrusions from Lab 5 -
  NICADD/FNAL Extruder
• However, the hole is oval and slightly oversize
• Highest light yield fiber tight in hole
• 0.5 m long and painted with TiO2
• Minerva electronics and MINOS pmt (M64) in MINOS
  PMT box
• 1.2 mm, 3.5 m, mirrored WLS fiber mirror at
  scintillator end
• Length simulates the worst case
• No clear 1 m cable in VST I
• must multiply the result by 0.75

8
VST I

• PE 1 Layer of triangles
• 10 pe scaling the single pe peak
• 12 pe - inefficiency with /10 optical filter in
  connector
• These agree well average 11 pe
• Scale to 110.75(for cable)8 pe/layer

9
Near Term Tests

• VST II - measure position resolution directly
• Jan Feb 2005
• All parts exists
• Use next generation of extrusions
• Measure position resolution
• Compare light between the 3 layers to show dE/dx
  resolution
• Compare to Monte Carlo program
• VST II is this decisive test
• Source R D Tests
• Illuminate a separate 5 triangles array with a
  source
• Compare light between different configuration
• Compare glue to no glue, etc.

10
NICADD/FNAL Extruder

• Extruded scintillator much cheaper than cast
  scintillator
• Can create unique shapes - MINERvA triangles
• FNAL group experienced with extruded scintillator
  MINOS, K2K
• Extruder is a collaboration between FNAL and
  NIU, owned by NIU
• Computer controlled
• Regulate mixture of polystyrene pellets and
  dopants
• Optimize temperature and extrusion speed
• The Extruder is the ideal size for MINERvA
  production

11
Extruder Dies

• Two scintillator shapes triangle and square
• Triangular extrusion is more challenging shape
• VST I first die
• Supported by FNAL, NIU, DOE-HEP through Rochester
• Re-tune for making triangular extrusions for VST
  II
• Development of new die for square scintillator
• Expected to be easier
• Co-extruder coat scintillator extrusion with
  TiO2
• MINOS scintillator manufactored with coextruder

12
Quality Control and Production

• Production run tolerances for triangular shapes
• Hole production and testing

13
Fiber Procurement

• Purchase 57 km of clear fiber Rochester Task
• QC same procedure as CMS
• Use cable testing box to inject light to fibers
• Test 5 fibers in batch ( a fiber preform)
• QC tests done by Rochester physicist and a
  Rochester technician
• Purchase 119 km of WLS fiber Rochester Task
• QC Lab 6 automatic fiber scanner, UV lamp and
  pin diodes
• Not working now
• Could use manual setup in Muon Lab source and
  PMT
• Measure 5 fibers from a batch
• Mirror fibers in Lab 7
• FNAL contribution budgeted in FNAL impact
  statement
• Lab 7 did this for CDF Plug, FOCUS, STAR ECAL,
  CMS HCAL, D0
• 3 steps ice polishing sputtering and protecting
  the mirror

14
Connector Procurement and Polishing

• DDK will design new ferrule for 1.2 mm fiber
  initial QC
• Measure initial connectors with Avant Optical
  Gauge Comparator
• Coordinate measuring machine owned by Tech
  Support
• They will measure the position and angle of holes
• Measure RMS of the light of initial set of cables
• Polishing at Lab 7
• Lab 7 has been polishing connectors for the last
  10 years
• They have experience polishing these connectors
  - FOCUS
• DDK connectors have fiberglass which dulls the
  diamonds
• New diamonds or relapped diamonds after 40
  connector polishes
• Lab 7 polishes 10 connectors at a time
• FNAL Lab 8 need to build fixture to hold the
  connectors

15
Optical Cables and ODU Assembly

• ODUs fibers-connector part used for the PMT box
• Like cable, but not made light tight
• Cable construction same techniques and CDF and
  CMS
• To make light tight copy MSU STAR method
• Put RTV boot on both ends of cable
• Can prototype existing DDK connectors for 1.0 mm
  fiber
• Fiber diameter doesnt matter for test certain
  techniques
• Test RTV light tight boot
• Set up the production line
• QC Build quality control device
• Build light injection box like CMS calibration
  box
• Build box to take light in cables to pin diodes
• Multi-channel pico-ammeter system readout out pin
  diodes

16
Scintillation Extrusion Schedule

• Schedule based on experience from extruder R D
• 2 dies 2 months of testing the tuning for each
  die
• 90 Days for production
• People
• 2 FNAL technicians
• NIU Production Coordinator 50 time
• NIU Run Supervisor 50 time
• 9 month after June 1 March 2005

17
Schedule

• WLS Fiber
• 3 months to acquire WLS fiber -
• 4 months to mirrors fiber 4 technicians
• June 2005 Dec 2005
• An Fall accelerator shutdown could effect this
  schedule
• Optical Cables and ODUs
• 3 months to acquire prototype ferrule
• 1 month to test
• 1 month acquire production connectors
• 1 Rochester RD Technician Finish Nov 2005
• 7.5months 2404 ODUs Rochester 4 techs
  Finish Jun 2005
• 12 months - 4607 Cables 6 techs - Finish Jun
  2006

18
Cable Costs

• As-real eng as realized and engineering costs
  estimate
• Exp as-real direct extrapolation from as
  realized costs
• Act as-real actual as realized costs
• Sim/exp as-real direct/similar extrapolation
  from as realized costs

19
Polishing and WLS Fiber Costs
20
Costs Scintillator Extrusions