NuMI

Schematic View of the MINOS Scintillator System

8 m

Scintillator Module

WL

S Fi

bers

WL

S Fi

bers

Optical Connector

Optical Connector

Optical Connector

Optical Connector

Cle

ar F

iber

Rib

bon

Cab

le (

2-6

m)

Cle

ar F

iber

Rib

bon

Cab

le (

2-6

m)

MultiplexBox

MultiplexBox

PMTs

Con

nect

ion

to

elec

tron

ics

Con

nect

ion

to

elec

tron

ics

• Extruded scintillator, 4.1 cm wide• Two-ended WLS fiber readout.• Strips assembled into 20 or 28-wide modules.• WLS fibers routed to optical connectors.• Light routed from modules to PMTs via clear fibers.• 8 Fibers/PMT pixel in far detector. (Fibers separated by ~1m in a single plane.)• 1 Fiber/PMT pixel in near detector (avoids overlaps).• Multi-pixel PMTs Hamamatsu M16 (far), M64 (near)

NuMI

Far Detector Module Layout

• 8 modules cover one far detector steel plane

• Four 20-wide modules in middle (perp. ends)

• Four 28-wide modules on edges (45 deg ends)

• Two center modules have coil-hole cutout

Coil B

ypas

s28

28

2828

2020

2020

NuMI

Near Module Layout

Some changes under study.New Picture In Development

NuMI

1.6

1.4

1.2

1.0

0.8

0.6

Est

imat

ed L

ight

Yie

ld

3200300028002600240022002000

Sample Number

Lower Limit of Acceptable Light Yield

UV at factory Source at FNAL

Extruded Scintillator

• Dow Styron 663 W polystyrene without additives• PPO and POPOP waveshifters (1% and 0.03% by weight)• 1.0 cm x 4.1 cm cross-section extrusion co-extruded with TiO2 reflector• Extruded groove for WLS fiber (which is glued into the strip)• Light output excellent for this collection geometry… better than commercial cast scintillator machined to shape and wrapped with Tyvek.

Rapid light output checks are important to establish and maintain high quality

Photo of ascintillator strip

41 mm 10 mm

As long as

desired

…Cross-section photo of two scintillator strips with fibers glued into grooves.

Light output measurements in Aug. 2000

Problemsfound and fixed!

Typical light yield in Nov. 2000

NuMI

WLS Fiber

• Kuraray WLS fiber:« 1.20 +0.024 -0.005 mm diam.

« 175 ppm Y11 fluor (K27)

« polystyrene core, double clad (PMMA and polyfluor)

« “Non-S Type”

Fiber spool inuse on the gluemachine.

Attenuation curves for severalfibers in the same batch fromKuraray (“batch” = 1000m)

Typical variation inlight from far end is ~3%.

Lig

ht (

arb.

uni

ts)

Position (m)

Variation in light from the far end of 8 m fibers from one batch to another has a sigma of about 5%.

Light vs Position in WLS Fibers

Typical “long attenuation”length ~6 m

NuMI

Module Components

• The scintillator modules are a laminate of scintillator strips (with WLS fiber glued into the groove) with aluminum skins.

• WLS fibers are routed through end manifolds to bulk optical connectors.

• The entire assembly is light-tight.

Assembly Drawing forside-out snout manifold

Bottom Al Cover

Bottom Al light case

Top Al light case

Top Al cover

Fiber routingmanifold

Connector

Top variablewidth seal

Bottom variablewidth seal

Light injectionmanifold

Light Case

Manifold base with fiber grooves

Formed Al cover

Light injection coverVariable width seal

Opticalconnector Module parts for “straight-out” manifold

NuMI

Clear Fiber

Typical response for a 3.5 m long cable compared to a reference 1m cable with ~90% absolute transmission.

Typical attenuation length ~ 14m!

20/28 Fibers per cable1.2 mm diam. Kuraray double clad fiber Clear fiber cables transmit light from modules to PMT boxes

Photo of a complete cable

connectors

shroudshroud

Coiled conduitwith fibers (loose)inside.

Schematic of a Cable

NuMI

PMTs

• Hamamatsu R5900 series multi-anode PMTs have been selected:« 16 pixel tubes for the far detector (pixel size 4mm x 4mm)

« 64 pixel tubes for the near detector (pixel size 2mm x 2mm)

• Gain of 106 consistent to x2 (M16) or x3(M64)

• QE at 520 nm typically 13.5%

• Good single pe peak

• Very fast signals and low time jitter.

M16M64

Cut-away viewof R5900 seriesPMT

16 mm

Fiber Layout

NuMI

PMT Measurements

NuMI

PMT Boxes and Connectors

Connector pair

Spring loaded PMT base

M16 PMT

PMT jacket

Adjustable mountingbracket (alignment)

Alignmentwindow (notinstalled)

Cookie with fibers

PMT MountingComponents

Front-end

electronics

• Far detector (shown)• 3 M16 PMTs/box• 8 fibers per pixel “optical multiplexing”• Each box serves 2 planes (one side)

NuMI

Light Injection System

• The light injection system provides short term PMT gain checks, linearity checks and monitoring of light transmission.

« 16 pulser boxes, 20 LEDs per box

« Light from each LED fanned out x 50

« Light distribution uniform to within a factor of 2

« Up to 150 pe’s observed at PMT channels

« 12 bit resolution on amplitude control

-7

-5

-3

-1

1

3

5

7

-7 -5 -3 -1 1 3 5 7

PIN Diodes

Module End Manifold

Light Injection Pockets

Acrylic fibers to distribute LED light

WLS Fibers

LEDPulse Boxes

Light fanout cone

Light fanout cone

Schematic of Light Injection System Relative light in fibers

Light Injection Prototype

NuMI

Calibration Detector

• The calibration detector is a small version of the “big detectors” to be exposed in test beams:

« 1 m square x 60 planes deep

« All technology as in MINOS near and far detectors (both technologies where there are differences.)

« Provide hadronic energy scale

« Detailed topology studies

« Calibration transported between detectors using cosmic ray muons

Waiting for drawingof detector.

NuMI

Automated Production Equipment

Automated Module Mapper with28 strip-wide module (8m x 1.2 m).Uses computer driven x-y scanningtable with 137Cs source.

Automatic Fiber Gluing Machine: Lays down bead of glue, unrolls fiber from spool, pushes fiber into glue in groove and covers the groove with a reflector.

Fibers at connector

Fiber spool

28 strip-wide module

Gluedispenser

Gluing apparatus

x-y bridge

source

Module

Light injection manifoldOptical connector

Clear fiber cable PM

T Box

Computer controland readout

NuMI

Module Factories

The “Gluing Room”

Racks filled with modules

Fiber Gluing Machine

Light Case assembly/forming

Overview of section of a factory

Mapper with short 45

Crimping/detailing table with long45 and lifting fixtureModule storage rack with 5 full assembly trays

Scintillator strip crates

MapperDAQ

Module withfibers glued in.

Module on shuttle table

NuMI

Assembled Scintillator Plane

NuMI

System Light Output

Light output vs position of cosmic ray muons passing nearly perpendicularly througha scintillator module averaged over all strips within a module. The light output is measuredusing the full MINOS readout apparatus (connectors, clear fibers, PMTs…). The lightread from each end of a module is shown along with the sum of light from each end.

One of the best modulesA typical 45o module

Note: The drop in light at the two ends is due to different lengths of strips at the ends.N

umbe

r of

obs

erve

d ph

otoe

lect

rons

Num

ber

of o

bser

ved

phot

oele

ctro

ns

Distance along the module (m) Distance along the module (m)

NuMI

Module Mapper Results

NuMI

4PP Operations

Trigger module

Trigger module

MUXBox

Con

nect

ors

Rabbit Crate

Clear Fiber Cables

Steel Octagon

Module M

anifolds

“Downstream View” “Edge View”

Cosmic ray muons are readout using an external trigger in the 4 Plane prototype(3 scintillator planes). Results are consistent with previous cosmic ray tests made one year earlier with the modules horizontal in the cosmic ray test stand.

NuMI

Cosmic Ray Muons in the 4PP

Typical single photoelectron spectrum from light injection

Used to determine PMT gains

pedestal

single pe peak

Number of observed photoelectronsper muon (corrected to 1 cm thickness)

Note: The data are from a small section ofthe 4PP where the trigger counters cover.

NuMI

Some Scintillator System Parameters

• Some major system features« Extruded Polystyrene Scintillator: 300 T, 600 km of 4.1x1.0 cm2 strips.

« WLS Fiber: Kuraray double-clad 1.2 mm diam., 175 ppm Y11, 780 km

« Scintillator Modules: 20/28 strips wide and up to 8m long. ~4300 mods., ~28,000 m2

« Clear Fiber: Like WLS, no fluor, 1100 km of fiber built into cables with 20/28 fibers.

« PMTs:

* Far detector: Hamamatsu M16 with 8 fibers per pixel with fibers readout from each side of the detector. 3 tubes per plane, ~1500 tubes

* Near detector: Hamamatsu M64 with one fiber per pixel and fibers readout from one side of the detector (with reflectors on the far end). ~200 tubes.

« Light Injection: Blue LED illumination of all WLS fibers to rapidly track PMT response.

• Performance Requirements:« Light output: > 4.7 observed pe’s on average for a MIP crossing.

« Time measurement: < 5 ns per plane for MIP crossing.

« Calibration:

* Relative near/far energy response to within 2%.

* Absolute hadronic energy response to within 5%.