extruded plastic scintillator for the minos …
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MINOS
EXTRUDED PLASTIC SCINTILLATOR FOR THE MINOS CALORIMETERS
Anna Pla-Dalmau
MINOS Scintillator Group
Fermilab
Calorimetry 2000 Workshop
LAPP - Annecy
October 12, 2000
MINOS
MINOS: MAIN INJECTOR NEUTRINO OSCILLATION SEARCH
MINOS
MINOS NEAR DETECTOR
• 16.6 m long, 980 tons
• 280 “squashed octagon” planes
• Forward section: 120 planes
4/5 partially instrumented
1/5 planes: full area coverage
• Spectrometer section:160 planes
3/4 planes not instrumented
1/4 planes: full area coverage
Coil hole
Beam fiducial region
Instrumented area
MINOS
MINOS FAR DETECTOR
MINOS
MINOS: 4 PLANE PROTOTYPE
MINOS
CAST SCINTILLATORS
ADVANTAGES• Fast response• Ease of manufacture• Versatile: plates, fibers, tiles
DISADVANTAGE FOR LARGE DETECTORS• Expensive: price of cast scintillator ~ $40/kgÔMINOS needs 300,000 kg of scintillator!
èOBJECTIVE:USE LOW COST SCINTILLATOR
MINOS
EXTRUDED SCINTILLATOR
TO LOWER COSTS: EXTRUDED SCINTILLATOR
ADVANTAGES:• Use commercial polystyrene (PS) pelletsÔMany grades, many prices
• Processing flexibilityÔManufacture of essentially any shape
DISADVANTAGES• Poorer optical qualityÔParticulate matter in PS pelletsÔAdditives in PS pellets
MINOS
EXTRUDED SCINTILLATORS
Ô Extrude a scintillator shape and use wavelength shifting (WLS) fibers as readout.
scintillator
1.2 mm WLS fiber
aluminized Mylar tape
optical epoxy
0.25 mm TiO2 reflective cap
10 mm
41 mm
MINOS
SELECTION OF RAW MATERIALS
BLUE SCINTILLATOR CORE• Polystyrene: Dow Styron 663 W• Dopants: 1% PPO + 0.03% POPOP
WHITE CAPSTOCKING• Polystyrene with 12% TiO2 – 0.25 mm thick
GREEN FIBER• K-27 fiber – 1.2 mm diameter
MINOS
MANUFACTURING TECHNIQUE
PS pellets and dopantmixture
EXTRUDER(64-mm single screw)
DIECO-EXTRUDER
(32-mm single screw)
Scintillator strip with white reflector coating
titanium dioxidemixture
MINOS
MANUFACTURING TECHNIQUE
DRYER
Dry PS purged with nitrogen
PS mixed with PPO+POPOP
PS mixture purged with nitrogen
Hopper purged with nitrogen
MINOS
EXTRUSION AT ITASCA PLASTICS
MINOS
EXTRUSION AT ITASCA PLASTICS
MINOS
EXTRUSION AT ITASCA PLASTICS
MINOS
EXTRUSION AT ITASCA PLASTICS
MINOS
EXTRUSION AT ITASCA PLASTICS
MINOS
EXTRUSION AT ITASCA PLASTICS
MINOS
EXTRUDED SCINTILLATOR STRIPS
MINOS
PRODUCTION SAMPLES
MINOS
QC: PROFILE DIMENSIONS
W H Groove Width Groove Depth h
Week 1Average 40.92 9.94 2.52 2.36 7.37
Std Deviation 0.02 0.07 0.16 0.09 0.07
Week 2Average 40.94 9.92 2.92 2.31 7.52
Std Deviation 0.02 0.06 0.17 0.05 0.08
Week 3Average 40.96 10.01 2.73 2.66 7.13
Std Deviation 0.02 0.07 0.14 0.14 0.09
All units in millimeters
W
H h
MINOS
QC: LIGHT YIELD
XenonLamp
Mono-chromator
Photomultiplier
Mono-chromator
Fiberoptics
Sample to be measured
450 nm
QC SETUP AT THE FACTORYCOMPARISON OF MEASUREMENTS
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
3250 3350 3450 3550 3650 3750 3850 3950 4050 4150 4250
SAMPLE NUMBER
LIG
HT Y
IELD
FNAL (Cs-source)
Itasca (UV)
Baseline
MINOS
QC: DOPANT CONCENTRATION
1.2
1.0
0.8
0.6
0.4
0.2
Inte
nsity
(rel
. to
A)
550500450400350
Wavelength(nm)
A
B
164% (1.34:1) 84% (1.12:1) 50% (1.06:1)
Fluorescence Spectrum320 nm excitation
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2000 2200 2400 2600 2800 3000 3200 3400
SAMPLE NUMBERP
EA
K R
ATI
O &
LIG
HT
YIE
LD
Cs LY
Peak Ratio
MINOS
LIGHT OUTPUTMAY 2000 MODULE PRODUCTION
Title:anl_c_14.ps (Portrait A 4)Creator:HIGZ Version 1.25/01Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.
Title:anl_c_14.ps (Portrait A 4)Creator:HIGZ Version 1.25/01Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.
Title:anl_c_14.ps (Portrait A 4)Creator:HIGZ Version 1.25/01Preview:This EPS picture was not savedwith a preview included in it.Comment:This EPS picture will print to aPostScript printer, but not toother types of printers.
AVERAGE SUMMED LIGHT OUTPUT > 7.0 pe
MINOS
CONCLUSIONS
• Extruded scintillator is being produced:• Industrial environment• Low cost• High quality material
• MINOS uses extruded scintillator:• Total of 300 tons• Cost: $6 per kg (vs. cast $40 per kg)• Average summed light output > 7 pe
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