Fermi National Accelerator Laboratory EXTRUDED SCINTILLATOR STRIPS FOR MINERVA Anna Pla-Dalmau Fermilab Victor Rykalin NICADD, Northern Illinois University Minerva Collaboration Meeting August 13-15, 2004

FNAL-NICADD EXTRUSION FACILITY

In-line continuous process: Less handling of raw materials Precise metering of feeders Twin-screw extruder (better mixing) Melt pump offers steady output Control instrumentation Line under nitrogen atmosphere: Drying under nitrogen Each piece of equipment is purged POLYMER DRYER CONVEYOR POLYMER FEEDER DOPANT FEEDER EXTRUDER MELT PUMP DIE OUTPUT: Scintillating pellets Scintillator bars

EXTRUSION TOOLING FOR MINERVA

EXTRUDED SCINTILLATOR STRIPS FOR MINERVA

SCINTILLATOR CHARACTERISTICS

Attenuation Length L=27.06 cm Attenuation Length L=29.42 cm LIGHT YIELD RATIO: 1.64 (TYVEK / NO-TYVEK)

SCINTILLATOR PROFILE STRIP SIZE: 32.1 mm by 16.6 mm – lip ~ 31 mm by 16.6 mm - round HOLE SIZE: mm by mm (OVAL) STRIPS AVAILABLE: - 50 cm long & round hole 44 STRIPS mm FIBER 38 STRIPS - <1.5 mm FIBER cm long & oval hole STRIPS

SCINTILLATOR PROFILE ROUND CORNERS VS. LIP AT THE BASE

CURRENT STATUS Reasonable triangle shape –Slightly small –Bowed / indented base – round corners –“Flatter” base – lip The die and/or the calibrator would need to be modified. Large and oval hole The pin needs to be changed. Strips show arching (upwards) at the ends –Stress caused by uneven cooling in the part

NEXT STEP Feedback from MINERVA –What is needed in the scintillator strips? –Will strips be glued? –What is the size of the fiber? Back to the die maker to address current problems –Likely to require additional funding FNAL number for the drawing Purchase polystyrene and dopants One more run “as is” to test air knife