TOWARDS A SCINTILLATOR BASED

1
TOWARDS A SCINTILLATOR BASED DIGITAL HADRON
CALORIMETER FOR THE LINEAR COLLIDER DETECTOR
ALEXANDRE DYCHKANT FOR NICADD/NIU AND UIC
Northern Illinois University (DeKalb, IL 60115,
USA)
2
OUTLINE
INTRODUCTION RESULTS PLANS SUMMARY
3
INTRODUCTION THE CURRENT TEVATRON RUN AT
FERMI NATIONAL ACCELERATOR LABORATORY AND
OPERATION OF THE LARGE HADRON COLLIDER AT CERN
ARE CLEAR PRIORITIES FOR THE PRESENT AND
IMMEDIATE FUTURE OF THE HIGH-ENERGY PHYSICS
FRONTIER. HOWEVER, NOW IS A GOOD TIME TO PLAN
AND PREPARE FOR THE NEXT STEP, A LINEAR EE-
COLLIDER, TO REVIEW TECHNOLOGIES FOR DETECTORS,
AND TO CLEALY POINT OUT AREAS WHERE R D WILL BE
NEEDED IN THE FUTURE. IN ORDER TO REALIZE THE
FULL POTENTIAL OF A FUTURE LINEAR ELECTRON
POSITRON COLLIDER, A DETECTOR SHOULD HAVE A
HADRON CALORIMETER WITH A DIJET ENERGY RESOLUTION
30/?E OR BETTER. MOST MODERN SAMPLING HADRON
CALORIMETERS HAVE 90/?E ENERGY RESOLUTION FOR
JETS WHICH CAN BE IMPROVED UP TO 50/?E USING
FLOW ENERGY ALGORITHMS. HOWEVER, IF ENERGY
FLOW ALGORITHMS ARE APPLIED TO A DETECTOR THAT
HAS A HIGHLY SEGMENTED HADRON CALORIMETER, THE
HITS FROM CHARGED PARTICLES CAN BE SEPARATED FROM
NEUTRAL PARTICLES IN A STRONG MAGNETIC FIELD BY
ASSOCIATION WITH CORRESPONDING TRACKS IN THE
INNER VOLUME. AFTER THAT, THE TRACKER WILL BE
USED TO MEASURE THE CHARGED COMPONENTS, AND THE
ELECTROMAGNETIC CALORIMETER WILL BE USED TO
MEASURE THE PHOTONS. EACH OF THEM PROVIDE HIGH
PRECISION ENERGY MEASUREMENTS.
4
INTRODUCTION THE HADRON CALORIMETER WITH
TRADITIONAL RESOLUTION WILL MEASURE THE ENERGY
OF NEUTRAL HADRONS ONLY, WHICH, ON AVERAGE,
DEPOSIT APPROXIMATLY 11 OF A JETS TOTAL ENERGY.
THUS, BECAUSE LINEAR COLLIDER DETECTOR ITSELF IS
OPTIMISED FOR ENERGY FLOW ALGORITHMS, A NET JET
ENERGY RESOLUTION OF 30/?E COULD BE ACHIEVED.
THE NEXT TWO SLIDES WILL PROVIDE THE RESULTS
OF THE SIMULATIONS OF ENERGY RESOLUTION AND
NUMBER OF HITS VERSUS THE SINGLE PARTICLE ENERGY
FOR CELLS OF DIFFERENT AREAS (CELLS ARE
PROJECTIVE IN ? AND ?).
5
Energy Resolution
single threshold
6
N vs. E
7
BY VARYING THE TRANSVERSE CELL SIZE, SIMULATIONS
INDICATE THAT THE ENERGY RESOLUTION FROM DIGITAL
MEASUREMENT IS BETTER THAN CORRESPONDING ANALOG
MEASUREMENTS. THIS SUPPORTS DIGITAL APPROACH TO
THE HADRON CALORIMETRY, AND FUTURE RESEARCH ON
ENERGY FLOW ALGORITHMS SHOULD INCLUDE
OPTIMIZATIONS FOR DIGITAL HADRON CALIRIMETER AS
WELL. OUR GROUP AT THE NORTHERN ILLINOIS CENTER
FOR ACCELERATOR AND DETECTOR DEVELOPMENT
(NICADD), AS A POSSIBLE SOLUTION, HAS UNDERTAKEN
A COMPREHENSIVE FEASIBILITY STUDY OF A SAMPLING
HADRON CALORIMETER WITH SMALL SCINTILLATING CELLS
AND 30 LAYERS OF ACTIVE MEDIUM. THE PROJECT
CONSISTS OF COMPUTER-BASED SIMULATIONS AND THE
PROTOTYPE, DEVELOPED CONCURRENTLY. THIS TYPE OF
CALORIMETER WILL HAVE UP TO 5 MILLION INDEPENDENT
PHOTO READOUT CHANNELS. BECAUSE THE AVERAGE
OCUPATION OF CELL WILL BE LESS THAN ONE, IT CAN
BE A DIGITAL SINGLE BIT READOUT WITH THE
THRESHOLD SET TO DETECT THE PASSAGE OF A MINIMUM
IONIZING PARTICLE (MIP). IT IS A PROVEN
TECHNOLOGY, BUT THE SCALE OF ITS APPLICATION IS
QUITE INNOVATIVE. EACH ACTIVE LAYER OF THE
CALORIMETER HAS A CYLINDRICAL SHAPE, WITH RADII
FROM 2 TO 3 M, AND 4 M LONG (IN CASE OF THE
SLCD). EACH 1 M2 OF ACTIVE LAYER CONSISTS OF
APPROXIMATELY A THOUSAND CELLS. EACH CELL HAS A
WLS FIBER THAT CAN BE CONNECTED TO A
PHOTODETECTOR DIRECTLY (INSIDE THE MAGNETIC
COIL), OR VIA CLEAR FIBER (OUTSIDE THE MAGNETIC
COIL). IN THE LAST CASE, AN ADDITIONAL GAP OF 3
MM FOR CLEAR FIBER ROUTING WILL BE NEEDED.
8
NICADD PROTOTYPE OF SDHCAL
Scintillating Digital Hadron Calorimeter (SDHCAL)
consists of the following major optical parts
scintillating cells, optical fibers, and photo
detectors. For the prototype, we thoroughly
investigated the response of the cells with
dimensions close to the Moliere radius (17 mm)
for a passive material used (that can be brass or
stainless steel). We are going to use
extruded scintillator to reduce the cost. Fibers
and photo detectors can be the most expensive
part of this project. In this presentation Im
going to show that the small scintillating cells
are a reasonable approach to DHCAL.
9
EXTRUDED SCINTILLATOR IS TEN TIMES CHEAPER THAN
CAST SCINTILLATOR. IT PROVIDES 60 OR MORE OF
LIGHT OUTPUT WHEN COMPARED TO BC408. EXTRUDED
STRIPS HAVE REGULAR DIMENSIONS AND UP TO 10
HOLES FOR WLS FIBERS INSIDE
Note Die provides exact shape and dimensions of
product
10

• FIBERS AND SCINTILLATORS
• THE FOLLOWING FIBERS WERE TESTED
• BICRON BCF-92 SQUARE, 0.8 MM SIDE
• BICRON BCF-92 ROUND, 0.8 MM OUTER DIAMETER
• BICRON BCF-92 ROUND, 1.0 MM OUTER DIAMETER
• KURARAY Y-11 ROUND, 0.94 MM OUTER DIAMETER
• KURARAY Y-11 ROUND, 1.0 MM OUTER DIAMETER
• (KURARAY CLEAR ROUND, 0.94 MM OUTER DIAMETER.)
• ALL FIBER ENDS WERE POLISHED USING FLY DIAMOND
  CUTTING TECHNIQUE. ONE END OF EACH WLS FIBER WAS
  ALUMINUM MIRRORED. ALL WLS FIBERS WERE 1 M LONG.
  THERMAL SPLICING FOR KURARAY ROUND 0.94 MM OUTER
  DIAMETER FIBERS WAS SUCCESSFULLY RE-TESTED BY
  FOLLOWING THE CMS PROCEDURE. KURARAY Y-11 ROUND,
  1.0 MM OUTER DIAMETER WLS FIBERS PROVIDE THE
  LARGEST RESPONSE, WHICH IS 3.14 TIMES LARGER THAN
  OUTPUT OF BCF-92 SQUARE 0.8 MM SIDE WLS FIBER.
• THE FOLLOWING SCINTILLATORS WERE TESTED
• BICRON BC-408 5, 10, AND 20 MM THICKNESSES
• ELJEN TECHNOLOGE EJ-200 3, 4, AND 5 MM
  THICKNESSES
• NICADD-FERMILAB EXTRUDED 5 MM THICKNESS.
• INFLUENCE OF THE FOLLOWING SIDE AND SURFACE
  TREATMENTS OF SCINTILLATING CELL RESPONSES, SUCH
  AS POLISHING, MACHINING, MIRRORING, PAINTING AND
  DIFFERENT KINDS OF WRAPPING, WERE STUDIED (TABLE
  1).
• RESPONSES OF HEXAGONAL AND SQUARE SHAPES CELLS
  WITH AREA 9 AND 6 CM² WERE TESTED. CELL
  RESPONSES, WITH STRAIGHT AND SIGMA FIBER GROOVE
  SHAPES, TAPERED AND ROUND HOLE GROOVES WERE
  TESTED, USING WLS FIBERS EMBEDED AND GLUED WITH
  OPTICAL GLUE.
• THE UNIFORMITY OF THE RESPONSES OF CELLS WITH
  STRAIGHT AND SIGMA GROOVE WERE MEASURED. RESPONSE
  VERSUS THICKNESS OF CELL WAS STUDIED AS WELL (THE
  FOLLOWING CHART).

11
CELL RESPONSES WITH DIFFERENT COATING/WRAPPING TH
E REASON FOR CARRYING OUT THESE MEASUREMENTS WAS
THE LACK OF DATA ON RESPONSE OF A SMALL
SCINTILLATING CELL WITH POLISHED EDGES COMPARED
TO THE RESPONSE OF A CELL WITH UNPOLISHED OR
JUST MACHINED EDGES, AND HOW THESE RESPONSES ARE
SENSITIVE TO DIFFERENT WRAPPING OR COATING
MATERIALS.
TABLE 1. RATIO OF CELL RESPONSE TO TYVEK (IN
PERCENTAGES)
Cell type Tyvek Paint VM 2002 Mylar CM590 CM500 Alum Foil
Mach. sides 100 87 108 83 28 44 63
Mach./ Polish 127 130 128 130 114 119 -
NOTE FOR DETAILS OF THIS MEASUREMENTS LOOK AT
THE LAST SLIDE.
12
THIS CHART REPRESENTS RESPONSE OF CELLS WITH
THICKNESSES of 3, 4, AND 5 MM. UNITS FOR
THICKNESS AND RESPONSE WERE NORMALIZED TO CELL
WITH 3 MM THICKNESS IN ORDER TO SIMPLIFY THE
FOLLOWING ANALYSIS. Cs-137 RADIOACTIVE SOURCE
WAS USED. THE RESPONSE IS A LINEAR FUNCTION OF
CELL THICKNESS UP TO 5 MM WITH THE SLOPE OF 0.84.
13
PHOTODETECTORS THE FOLLOWING PHOTODETECTORS
WERE USED FOR DIFFERENT TESTS VLPC, HAMAMATSU
PMT R-580, HAMAMATSU MPMTs H8711. ALSO,
HAMAMATSU Si APD S8550 AND SiPM FROM PULSAR
ENTERPRISE, RUSSIA ARE CURRENTLY UNDER THE TEST.
14

MEASUREMENTS WITH H8711
COSMIC TRIGGER PROVIDES PARTICLES WITH TRACKS
PERPENDICULAR TO THE STACK OF CELLS 2 ? OF BRASS
ARE INSTALLED BETWEEN THE LAYERS WE USE VME
CRATE WITH QDC V792 AND LABVIEW DAQ EACH CELL,
MADE FROM 5 MM THICK BC408 SCINTILLATOR , HAD A
HEXAGONAL SHAPE WITH 3 MM DEEP SIGMA GROOVE, 9.4
CM² KURARAY Y-11 WLS FIBER WITH MIRROR, END
WAS GLUED INSIDE AND SPLICED TO 2 M LONG CLEAR
FIBER Ø 0.94 MM, TOP CHART SHOWS A MIP
RESPONSE, MIDDLE AND BOTTOM CHARTS SHOW
THE RESPONSE OF LED SIGNALS SIGNIFICANTLY ATTENUAT
ED WITH FILTER TO GET SES USING THE POISSON
DISTRIBUTION THE ESTIMATED AMOUNT OF PE ARE 0.95
AND 0.6 ACCORDINGLY, MPMT SHOWS APPROXIMATELY
10 PE.
15
CONCLUSIONS
THE NICADD- FERMILAB EXTRUDER HAS PRODUCED FIRST
SCINTILLATING STRIPS. OPTICAL CHARACTERISTICS OF
SMALL CELLS DIFFER FROM NORMAL SIZE TILE BECAUSE
ATTENUATION LENGTH DOES NOT WORK SURFACE
TREATMENTS DONT AFFECT THE RESPONSE, BUT
MACHINING SIDES DO. TODAYS DESIGN OF OPTICAL
ELEMENTS CAN PROVIDE 10 PE. WLS FIBER IS THE
MOST SENSITIVE PART IN OPTICAL READOUT. CELLS,
PAINTED IN ACRILIC TITANIUM WHITE, PROVIDE
RESPONSE THAT IS COMPARABLE TO A CELLS WRAPPED IN
TYVEK. PAINTING IS MORE PRODUCTIVE THAN WRAPPING
CROSSTALK BETWEEN WHITE PAINTED CELLS IS
SMALL. THE NICADD PROTOTYPE OF SDHCAL IS BEING
TESTED USING COSMICS RAYS NEW PHOTODETECTORS
WILL BE USED IN THIS STUDY AND NEED FURTHER
RD DIGITAL HADRON CALORIMETER WITH SMALL
SCINTILLATING CELLS IS A PLAUSIBLE SOLUTION FOR
THE FUTURE LINEAR COLLIDER DETECTOR. FURTHER RD
IN SCINTILLATING DIGITAL HADRON CALORIMETRY OPENS
NEW OPPORTUNITIES IN FUTURE FULL-IMAGING
CALORIMETRY.
16
    
       Acknowledgments   The authors
are thankful to Peter Torres and Daniel Ruggiero
for their help during the cell tests. We would
like to thank Phill Stone who provided excellent
mechanical support.                
 
References   1 C.Damerell et al., pg. 431, and
J.Brau et al., pg.437, Proc. Swnowmass 1996. 2
O. Lobban et al., On the Energy Measurement of
Hadron Jets, Proceedings of the Tenth
International Conference on Calorimetry in
Particle Physics, Pasadena, 2002. World
Scientific, Singapore, 2002,
p.814-833. 3 TESLA Technical Design Report,
DESY, March 2001. 4 SAINT-GOBAIN (Bicron),
12345 Kinsman Road, Newbury, OH 44065, USA. 5
CMS The Hadron Calorimeter Project Technical
Design Report CERN/LHCC 97 CMS TDR 2, 20
June 1997. 6 HAMAMATSU CORPORATION, 360
Foothill Road, P.O.BOX 6910, Bridgewater, NJ
08807-0919, USA 314-5, Shimokanzo,
Toyooka-village, Iwata-gun, Shizuoka-ken,
438-0193 Jap1. 7 Keithley Instruments, Inc.,
28775 Aurora Road, Cleveland, OH 44139, USA. 8
The MINOS Detectors Technical Design Report.
NuMI-L-603, March 1, 1999. 9 A. Bross et al.,
The Digital Hadron Calorimeter (DHC) Elements
Test, FERMILAB-TN-733, April 2003. 10
Kuraray America Inc., 200 Park Ave, NY 10166,USA
3-1-6, NIHONBASHI, CHUO-KU, TOKYO
103-8254, JAPAN. 11 Pulsar Enterprise,
Okruzhnoj Proezd 27, Moscow, Russia.
17
CELLS RESPONSE TO DIFFERENT COATING/WRAPPING
THE REASON FOR CARRYING OUT THESE MEASUREMENTS
WAS THE LACK OF DATA ON THE RESPONSE OF A SMALL
SCINTILLATING CELL WITH POLISHED EDGES COMPARED
TO THE RESPONSE OF A CELL WITH NON-POLISHED OR
JUST MACHINED EDGES AND HOW ARE THESE RESPONSES
SENSITIVE TO DIFFERENT WRAPPING OR COATING
MATERIALS.
GEOMETRY, MATERIALS, AND TOOLS
CELL MATERIAL SCINTILLATOR BC408,
THICKNESS 5 MM, SHAPE HEXAGON, AREA-
9.4 CM², 5 CELLS HAVE FINISHED EDGES
ALL TOTAL-11 CELLS.
GROOVE SIGMA SHAPE, RADIUS 12 MM, 25º OF
CIRCLE WITHOUT GROOVE, RECTANGULAR
CROS-SECTION, WIDTH 1 MM, DEPTH
4.5 MM AND TAPERED TO EXIT.
WLS FIBER BCF92, SQUARE, SIDE 0.8 MM, LENGTH- 1
M,FINISHED ENDS, ONE END MIRRORED,
EMBEDDED AND GLUED INTO THE GROOVE
USING BC600.
WRAPPING MATERIALS TYVEK, 3M CM500, 3M CM590,
3M VM2002, ALUMINIZED MYLAR,
TITANIUM WHITE ACRYLIC PAINT FROM LIQUITEX
ENGLAND, (ALUMINUM FOIL).
PHOTOMULTIPLIER TUBE HAMAMATSU R580, HIGH
VOLTAGE 1300V, DARK CURRENT
LESS THAN 0.07
NA, OR LESS THAN 0.1 WITH Sr90 (2 mC) Note
Painting is the most attractive solution because
of high productivity.