# Presentation: 659701

## Extruded Scintillator R&D at Fermilab

**Studied Wavelength shifting (WLS) fiber readout of scintillator extrusions for possible future large scale detectors**
**Scintillator: MINOS extrusions**
**1 X 4 cm – grooved**
**TiO****2**** reflector**
**Scintillator: KEK prototype**
**1.2 X 2.5 cm – hole down the middle**
**TiO****2**** reflector**
**WLS: Kuraray Y11**
**1.2 mm 175 ppm (MINOS Standard)**
**1.0 mm 200 ppm**
**0.5 mm 200 ppm**
**Photodetector - Visible Light Photon Counter (VLPC)**
**Used D0 HISTE VI devices**
**QE=80-85%**
**Gain ******** ****60,000**
**Tested double-ended readout of MINOS part and single-ended (mirror at far end) readout of KEK part so far**
**Cosmic Ray Trigger**

## Extruded Scintillator R&D

**Experimental setup**
**Three-fold CR trigger using MINOS or KEK extrusions +VLPC readout.**
**Test scintillator 30 cm long**
**WLS fibers**
**Double-ended – 9 m and 3.5 m**
**Single-ended – 11 m**
**WLS readout fiber moved in scintillator**
**Test scintillator + CR trigger stationary**
**WLS fiber coupled to 0.965 mm non-doped fiber to bring optical signal to VLPC cassette****	**
**Required area correction factor for 1.2 mm WLS fiber case **
**Data shown use optical coupler (BC 600 epoxy resin) between WLS fiber and scintillator**
**0.5 mm WLS fiber readout of MINOS extrusions shows data for optical coupler and without optical coupler**

## Tests with MINOS scintillator

**1.2 mm WLS fiber (MINOS equivalent) results**

- MINOS Ref. Value (sum)

## Tests with MINOS scintillator

**1.0 mm results**

## Tests with MINOS scintillator

**0.5 mm results**

## MINOS Scintillator with LC Muon Geometry

- Preliminary

## Double-ended WLS readout

**Double-ended Readout Observations**
**The 1.2 mm case agrees well with MINOS data (WLS fiber attenuation length, increase in yield due to optical coupling fluid (******** ****1.5), etc).  Yield much higher due to VLPC QE.**
**The 1.0 mm data also gives ******** ****1.5 for the ratio of yield with and w/o optical coupling. If one assumes that the ratio of the yield for a given scintillator readout with WLS fibers of diameter d****1**** and d****2**** goes like:**
**Y****1****/Y****2**** = (d****1****/d****2****)****n****  ********n = 1.48**
**The 0.5 mm case shows a much smaller increase in yield due to the epoxy resin and its yield relative to the 1 mm case gives ****n= 1.8**** as defined above**
**Comments**
**WLS doping concentration not optimized for 1 and 0.5 mm cases**
**Scintillator Groove shape fixed – not necessarily optimized for 1 and 0.5 mm cases**

## Tests with KEK scintillator

**Single-ended WLS fiber readout measurements.**

-   6.5 m

## Single-ended WLS readout

**First observation is that the attenuation length for this case is essentially equivalent to the MINOS double-ended 0.5 mm WLS fiber readout ******** ******** ****6.5 m)**
**Small improvement in effective ******** with mirror**

## Single-ended WLS readout

**Fiber attenuation length is not a strong function of fiber diameter**
**Kuraray makes DAMN GOOD FIBER!**

- 1 mm WLS fiber
- Essentially same  as 0.5 mm fiber

## Extruded Scintillator R&D

**Plans**
**Continue study with existing components (extrusions, WLS fibers)**
**Optimize for a given geometry**
**New extrusions**
**WLS fiber with optimized doping concentration**
**Test scintillator from new Fermilab scintillator extrusion facility once it is up and running (Summer 03)**
**Co-extrusion of WLS fiber with scintillator extrusion**
**Use commercial WLS fiber (Kuraray) and “post-clad” it with the scintillator**
**Already prototyped with thin layers (50 micron), but many issues still to be addressed**
**Heat soak to WLS fiber**
**Optical coupling to photodetector**

## LC Muon System Specific comments

**With current measurement light yield**
**Probably can go down to 350 micron WLS fiber**
**Need to Optimize**
**Scintillator groove (or hole)**
**Scintillator and WLS type**
**Primary only Scintillator?**
**Then can use 3HF WLS fiber**
**Would then allow 7:1 Multiplexing to standard D0 1 mm VLPC pixel**