Transcript Schematic View of the MINOS Scintillator System

NuMI
Schematic View of the
MINOS Scintillator System
Optical Connector 8 m Optical Connector
Connection to
electronics
Multiplex
Box
Optical Connector
Connection to
electronics
Optical Connector
PMTs
Multiplex
Box
Clear Fiber Ribbon Cable (2-6 m)
WLS Fibers
WLS Fibers
Clear Fiber Ribbon Cable (2-6 m)
• 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)
Scintillator Module
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
28
28
20
20
20
20
28
28
NuMI
Near Module Layout
Some changes under study.
NuMI
Extruded Scintillator
Light output measurements in Aug. 2000
Typical light yield in Nov. 2000
Estimated Light Yield
1.6
Photo of a
scintillator strip
1.4
Cross-section photo
of two scintillator
strips with fibers
glued into grooves.
1.2
1.0
0.8
0.6
Lower Limit of Acceptable Light Yield
Rapid light output
checks are important
to establish and
maintain high quality
2000
2200
2400
2600
Problems
found and fixed!
UV at factory
Source at FNAL
2800
3000
3200
41 mm
10 mm
Sample Number
• 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.
NuMI
WLS Fiber
Light (arb. units)
Light vs Position in WLS Fibers
Attenuation curves for several
fibers in the same batch from
Kuraray (“batch” = 1000m)
Typical “long attenuation”
length ~6 m
• 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 in
use on the glue
machine.
Typical variation in
light from far end is ~3%.
Variation in light from the far end of 8 m fibers
from one batch to another has a sigma of about 5%.
Position (m)
NuMI
Module Components
Top variable
width seal
Assembly Drawing for •
side-out snout manifold
•
Top Al cover
•
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.
Top Al light case
Fiber routing
manifold
Light Case
Connector
Manifold base with fiber grooves
Bottom Al light case
Variable width seal
Bottom Al Cover
Light injection cover
Light injection
manifold
Bottom variable
width seal
Optical
connector
Formed Al cover
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.
shroud
Coiled conduit
with fibers (loose)
inside.
shroud
connectors
Photo of a complete cable
Typical attenuation length ~ 14m!
Schematic of a Cable
20/28 Fibers per cable
1.2 mm diam. Kuraray double clad fiber
Clear fiber cables transmit light from modules to PMT boxes
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.
Fiber Layout
16 mm
M16
M64
Cut-away view
of R5900 series
PMT
NuMI
PMT Measurements
NuMI
PMT Boxes and Connectors
Cookie with fibers
PMT Mounting
Components
Alignment
window (not
installed)
PMT jacket
M16 PMT
Spring loaded PMT base
Connector pair
Adjustable mounting
bracket (alignment)
• 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.
Light Injection Prototype
« 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
PIN Diodes
Light
fanout
cone
7
Acrylic fibers to distribute LED light
5
3
Module End Manifold
Light
fanout
cone
LED
Pulse
Boxes
1
-7
WLS Fibers
-5
-3
-1
1
3
5
7
-1
-3
-5
Light Injection Pockets
Schematic of Light Injection System
-7
Relative light in fibers
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 drawing
of detector.
NuMI
Automated Production Equipment
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.
Automated Module Mapper with
28 strip-wide module (8m x 1.2 m).
Uses computer driven x-y scanning
table with 137Cs source.
Computer control
and readout
Fiber spool
Glue
dispenser
x-y bridge
Gluing apparatus
source
Module
Light injection manifold
Optical connector
Fibers at connector
NuMI
Module Factories
Light Case assembly/forming
Fiber Gluing Machine
Racks filled with modules
The “Gluing Room”
Overview of section of a factory
Mapper
DAQ
Mapper with short 45
Module with
fibers glued in.
NuMI
Assembled Scintillator Plane
NuMI
One of the best modules
Distance along the module (m)
Number of observed photoelectrons
Number of observed photoelectrons
System Light Output
A typical 45o module
Note: The drop in light at the two ends is due
to different lengths of strips at the ends.
Distance along the module (m)
Light output vs position of cosmic ray muons passing nearly perpendicularly through
a scintillator module averaged over all strips within a module. The light output is measured
using the full MINOS readout apparatus (connectors, clear fibers, PMTs…). The light
read from each end of a module is shown along with the sum of light from each end.
NuMI
Module Mapper Results
NuMI
4PP Operations
MUX
Box
Connectors
Trigger module
Trigger module
“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
Number of observed photoelectrons
per muon (corrected to 1 cm thickness)
pedestal
single pe peak
Used to determine PMT gains
Note: The data are from a small section of
the 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: s < 5 ns per plane for MIP crossing.
« Calibration:
* Relative near/far energy response to within 2%.
* Absolute hadronic energy response to within 5%.