Nuclear Instruments and Methods in Physics Research A 420 (1999) 48—61

Mass production of tile/fiber units for
the CDF plug upgrade EM calorimeter
S. Aota , T. Asakawa , K. Hara , E. Hayashi , S. Kim , K. Kondo , T. Kuwabara ,S. Miyashita , H. Nakada *, I. Nakano , Y. Seiya , T. Takebayashi ,K. Takikawa , H. Toyoda , T. Uchida , K. Yasuoka , M. Mishina, J. Ioveri
Institute of Physics, University of Tsukuba, Ibaraki 305, Japan Fermi National Accelerator Laboratory, Japan Waseda University, Japan
Received 8 June 1998

Abstract
We have fabricated scintillating tile/fiber units for the CDF plug upgrade electromagnetic calorimeter. The total
number of tile/fiber systems amounts to &23 000. We describe the quality control tests of scintillator plates, opticalfibers, and tile/fiber units which we placed at various stages in the fabrication procedures. We have completed the
production retaining the tile/fiber units which satisfy our requirements.  1999 Published by Elsevier Science B.V. All
rights reserved.
PACS: 29.40.Mc; 29.40.Vj
Keywords: Calorimeter; Scintillator; Tile/fiber; Mass production; Quality control; CDF

1. Introduction
The CDF (Collider Detector at Fermilab) plugcalorimeter will be upgraded in 2000 replacing thegas calorimeter [1,2]. The new plug electromagnetic (EM) calorimeter was designed to take full
benefits of the accelerator upgrade. It is a plasticscintillator-based sampling calorimeter consistingof scintillator plates with embedded optical read-* Corresponding author. Tel.: #81 298 53 4270;#81 298 53 4491; e-mail: housai@hep.px.tsukuba.ac.jp.

fax:

out fibers (tile/fiber) and lead absorber plates. With
this new calorimeter, substantial improvements are
expected in fast response, small dead space, andgood energy resolution comparing to the previous
gas calorimeter. We performed R&D for the newplug EM calorimeter from October 1990 to June
1993 [3—5]. The mass production of tile/fiber units
was started in October 1993 and completed in
February 1994. We monitored and controlled thequality of scintillating tiles and optical fibers at
various stages in the production. The results of ourquality checks satisfy the criteria required for goodenergy resolution and good response linearity.

0168-9002/99/$ — see front matter  1999 Published by Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 8 - 9 0 0 2 ( 9 8 ) 0 1 1 3 5 - 8

S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

49

We report on our quality control and the results inthis note.
We begin by describing the CDF EM calorimeterand our requirements for the tile/fiber system in Section 2. A number of our quality control tests performed during the tile/fiber production are describedin Section 4. The conclusion is given in Section 5.

2. CDF plug electromagnetic calorimeter2.1. Tile/fiber
The CDF tile/fiber EM calorimeter consists of 23
layers of sampling devices of a scintillating tile with
an embedded wavelength shifting fiber (WLS fiber),
23 lead absorber plates clad with stainless-steel
plates, and a shower maximum position detector
installed behind the 5th layer. The sampling tile/fiber
layer is divided to 24 units. One unit covers an
azimuthal angle of 15° as shown in Figs. 1 and 2,
and is called “15° unit” hereafter. A 15° unit consistsof 20 tiles for the 1st to 15th layers and 18 tiles forthe 16th to 23rd layers, plastic plates at top andbottom, and two sheets of polystyrene-terephthalate (PET) film used as reflector. A tower of thecalorimeter has a projective tower geometry andcovers a certain solid angle with respect to thenominal collision point. Tiles within a tower havea tile number, which is the tower number, but thephysical sizes are different in depth in the tower.
The tile number assignment is given in Fig. 2.
We chose Kuraray SCSN38 as the material of
scintillating tiles and Kuraray Y11 WLS and clear
fibers. These fibers with strong-type cladding are
multi-clad-type fibers and have polystyrene for thecore, polymethylmethacrylate for the inner clad,and fluorinated polymer for the outer clad. A Y11
WLS fiber with a diameter of 0.83 mm is thermallyspliced to a clear fiber with the same diameter [6].
The clear fiber is then connected to another clear
fiber of 0.90 mm diameter through a mass fiberconnector. The 0.90 fiber is connected further toanother clear fiber of 1.0 mm diameter througha mass fiber connector (see Fig. 1). These clear
fibers have plastic sheath for protection. The otherend of the WLS fiber is mirrored by aluminum
sputtering with a cover of MgF [7]. Light yieldedFig. 1. A schematic figure of a 15° unit and the readout path.

Fig. 2. Tile number assignment in a 15° unit. A 15° unit consistsof 20 tiles for layers 1—15 and 18 tiles for layers 16—23.

in a scintillating tile is collected by the WLS fiber
embedded in the tile, transmitted through the clear
fibers, and finally read out with a photomultipliertube (PMT).

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S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

2.2. Requirements
The energy resolution is given by  p p"  #(p ),

E
(E

(1)

where the first term p /(E comes from the sampling fluctuation and the photostatistics of PMTs,
and the second term p comes from the non-uni
form response of the calorimeter. We have estimated the sampling fluctuation for 4.5 mm thicklead plates to be 14%/(E using a shower simulation [1,2]. The new EM calorimeter is required thatthe stochastic term p should be less than 16% and
the constant term p be less than 1%. Non-linearity

of the calorimeter is required to be less than 1% in
the energy range between 10 and 400 GeV. To
fulfill the above criteria we requireFig. 3. Typical setup for the light yield measurement.

1. light yield from a tile/fiber be more than 3
photoelectrons (pes) per minimum ionizing particle (MIP),
2. response non-uniformity within a tile be lessthan 2.5%,
3. response variation of tiles within a tower be lessthan 10%, and
4. a total of light leakage from a tile to the adjacenttiles be less than 3.5%.

digitized by a LeCroy 2249A CAMAC ADC module. The trigger counter which is placed beneath thetile/fiber consists of a trigger scintillator (2—5 mm indiameter), an acrylic light guide, and two PMTs
(Hamamatsu H1161). We use a coincidence between signals from both the PMTs as the trigger
signal in this measurement.

More details are described in Refs. [1,2].

We estimate the light yield from the tile/fiber interms of average number of photoelectrons produced from the PMT photocathode. The average
number of photoelectrons is more universal than
average current or average electric charge from
PMTs; it does not depend on the gain of the PMTor the intensity of the source, but depends on thelight yield and the quantum efficiency of the photocathode.
We measured light yield from scintillator plates
and tile/fiber systems in the following way: An
average number of photoelectrons is calculated using a PMT pulse height distribution with typically3000 events. The pulse height distribution isa smeared Poisson distribution. The average number of photoelectrons can be determined from thepulse height distribution once we know the pulse
height for the single photoelectron. The pulse
height for the single photoelectron is measured

3. Light yield measurement
3.1. Experimental setup
A typical experimental setup for our light yieldmeasurement is shown in Fig. 3. We excite a scintillating tile with a Sr b-ray source. The source hasa lead collimator of 5 mm in diameter. Light fromthe tile/fiber is converted to electric signal by
a PMT (Hamamatsu H1161GS or R580-17 greenextended type). The signal from the PMT is These are green-extended-type PMTs and have a quantum
efficiency typically 15% higher than standard PMTs of
H1161(R329) or R580 for green light of approximate 500 nm
wavelength. H1161GS has more dynode stages than R580-17,
thus has a higher gain.

3.2. Light yield

S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

51

Fig. 4. A single photoelectron distribution (left) and a pulse height distribution in units of the single photoelectron peak (right).

with the same experimental setup by sufficiently
reducing the light intensity. In the measurement ofa single photoelectron pulse height, light yield istypically &0.1 photoelectrons. Fig. 4 (left) showsa typical pulse height distribution obtained in thismeasurement. The first peak at 22 ADC counts isthe pedestal and the second peak at 43 ADC counts
corresponds to the single photoelectron. Contribution from events with two or more photoelectrons
is negligible. In order to determine the peak position precisely, we fit the distribution near the peakwith a single Gaussian distribution. The fitted
curve is shown in the figure. The next step is todetermine the average number of photoelectrons
from the pulse height distribution. The average
number of photoelectrons (N ) is given by

X !X
,
N , 
(2)
 X !X
where X is the average ADC counts of the givenpulse height distribution, X is the single photo
electron peak counts, and X
is the pedestal
counts. Fig. 4 (right) shows a typical pulse height
distribution in which the x-axis is scaled in units ofthe single photoelectron peak.

Fig. 5. The procedure of the mass production and the quality
control performed during the production.

4. Quality control
Shown in Fig. 5 is the procedure of the tile/fiber
production. We checked the quality of tiles andfibers at several stages in the mass production. We
begin by describing the scintillator production andthe quality control.

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S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

4.1. Scintillator plate production
Scintillator boards, “mother boards”, are produced by Kuraray. The size of the mother board is2400 mm;1400 mm;4 mm. We produced 240
mother boards from 10 lots in total. The motherboard production was done in two periods; in thefirst period, 60% of the total were made andin the second the rest were made. From eachof mother boards we cut out four pieces of scintillator plates (470 mm;1400 mm;4 mm). Light
yield of the scintillator plate mainly depends
on the plate thickness and the chemical concentration of the wavelength shifter. To ensure uniform response over a tile/fiber system, these two
characteristics should be uniform. We checked
thickness and response uniformity of scintillator
plates. We also compared the quality of scintillator
plates produced in the two different periods
each other.
4.1.1. Plate thickness measurement
The nominal thickness of scintillating tiles is
4.0 mm. We required the thickness of scintillator
plates should be 4.0 mm with a tolerance of 0.2 mm.
The experimental setup for the thickness
measurement is shown in Fig. 6. The distance between the top and bottom surfaces of the scintillator plate is measured with differential transducers
with a resolution of &5 lm. In the system there
are five pairs of transducers with an interval of
25 cm. When the scintillator plate is scanned along
the direction parallel to the shorter (longer) side of
the plate, the plate thickness was measured at 5 (2)points with 5 (2) pairs of transducers at the sametime (see Fig. 7). We recorded the plate thickness at
every 1 cm during the plate scan. Peripheral area of
scintillator plates (5 cm or less inside the plateedges) was excluded in this measurement; the thickness in that area was known to be non-uniform andthe region was cut out in the tile production. The
plate thickness was measured at 482 points in eachplate.
The measured distribution of the plate thickness
is shown in Fig. 8. We obtained the acceptable
results that the average thickness is 3.983 mm andthe rms variation is 0.065 mm (1.6%). The results
are summarized in Table 1.

Fig. 6. Experimental setup for the plate-thickness measurement.

Fig. 7. The measured points in a plate. Plate thickness is measured along the dashed lines. The shaded area was excluded in
the measurement.

4.1.2. Light yield of scintillator plates
We sampled scintillator blocks with dimensionsof 20 mm;30 mm;4 mm from scintillator plates
and measured the light yield to check the uniformity of the wavelength shifting material. We sampled(i) one scintillator block per mother board in orderto monitor the variation between different motherboards and (ii) 12 blocks per mother board per lot

S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

53

Fig. 9. Experimental setup for the light yield measurement of
scintillator blocks.

Fig. 8. A distribution of the plate thickness for all motherboards. We obtained the average thickness of 3.983 mm and theRMS variation of 0.065 mm.

Table 1
Summary of the plate thickness measurement
Production

1st (60%)

2nd (40%)

Total

Ave. thickness (mm)Variation (%)

4.0
1.6

4.0
1.5

4.0
1.6

variation after the block thickness correction beless than 2%. The results of this measurement are
shown in Fig. 10: (a) the reproducibility of thismeasurement, (b) the light yield of scintillator
blocks before the thickness correction, (c) the thickness of scintillator blocks, and (d) the light yield
after the thickness correction. The light yields of all
sampled blocks were measured to be more than
7.0 pes. The variation of the thickness-corrected
light yield was 1.7% after subtracting 1% of thesystematic error. We summarize the results inTable 2. These results satisfy our requirements.
4.2. Fiber productionin order to monitor the variation within a motherboard. The light yield of the scintillator plate depends on the plate thickness. In order to extract thevariation of the light yield due to the non-uniformity of the wavelength shifter, we scaled the measured light yield to that expected for the nominal
plate thickness of 4 mm using the measured thickness.
The experimental setup is shown in Fig. 9. We
used an electromagnetic (EM) shutter and a quartz
glass in front of the PMT so that we could keep the
PMT high voltage on and hence keep the PMT
gain stable during the measurement. The lightintensity of the sample block was reduced to 5% by
a neutral density (ND) filter and air gaps between
the sample block and the PMT. Uncertainty of thelight yield measurement with this system is 1%. In
this measurement we required that the light yield of
a block should be more than 6 pes per MIP, and theFibers were produced in “batch” in which preforms with the same chemical mixture were used.
Fibers from the same batch, therefore, can bethought to have almost the same chemical
quality. In order to control the quality of fibers, wechecked1. diameter of clear and WLS fibers,
2. light attenuation length of clear and WLS fibers,and3. light yield of WLS fibers with a standard scintillating tile.
We use clear fibers with three different diameters ( "0.83, 0.90, 1 mm) as mentioned in Section 2. We report on our quality test for the WLS
fibers and the 0.83 and 0.90 clear fibers in this
note.

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S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

Fig. 10. Results of the light yield measurement of scintillator blocks: distributions of (a) the reproducibility of the measurement, (b) thelight yield of scintillator blocks, (c) the measured block-thickness, and (d) the thickness-corrected light yield are shown.

Table 2
Summary of the light yield measurement of scintillator blocks.
The minimum light yield, the light yield variation in all samples,and our requirements are listed

Table 3Nominal fiber diameters and our requirements
Fiber

Nominal diameter (lm)

Tolerance (lm)Production

WLS
Clear
Clear

830
830
900

$20
$20
$20

1st (60%) 2nd (40%) Total

Minimum light 7.0
7.5
yield (pes)
Variation (%)
1.8$0.1 1.5$0.2

7.0

Requirement'6

1.7$0.1 (24.2.1. Diameter
Nominal diameters and our requirements on thefiber diameters are summarized in Table 3. For
WLS fibers, we sampled a 3 m long fiber out of
every 100 m of WLS fiber. The diameter of the fiber
was measured at every 5 cm with a resolution of
0.1 lm. Fibers with diameters out of the specifications were rejected. For clear fibers, we cut thefibers after the fibers were covered. Therefore,
we measured diameters of the fibers andmarked the regions where the measured diameters
were out of the specification. The bad regions were
not used.
4.2.2. Light attenuation length
We measured light attenuation length of WLS
fibers and clear fibers. We require that the attenuation length of the WLS fibers and the clear fibers

S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

55

Fig. 12. A distribution of the attenuation length of 3 m long
WLS fibers.

Fig. 11. Experimental setup for the attenuation length measurement of WLS fibres.

should be more than 1.5 and 10 m, respectively, andtheir variations be less than 15%.
For WLS fibers, we sampled a 4 m long fiber outof every 50 m of WLS fiber after the diametermeasurement. The 4 m fiber was then divided into
a 75 cm long fiber and a 3 m long fiber, which wereused in the light yield and the attenuation length
measurements, respectively. Shown in Fig. 11 is theexperimental setup for the attenuation length
measurement. The light intensity was measured byreading the current of a PMT (Hamamatsu R64701) while exciting the fiber from the side with an
LED at 5 cm intervals. Note that the wavelength of
the LED lamp was &470 nm.
We obtained the attenuation length by fitting theplot of the light intensity vs. LED position witha single exponential function. The distribution of
the attenuation length of the WLS fibers is shownin Fig. 12. The average attenuation length and its
variation were measured to be 308 cm and 3.6% in
RMS, respectively.

Fig. 13. A distribution of light intensity vs. wavelength of the
halogen lamp used in the attenuation length measurement ofclear fibers.

For clear fibers, we sampled a pair of 15 m longclear fibers at the beginning and the end of eachbatch. We use a halogen lamp as a light source. The
wavelength distribution of the light from the halogen lamp is shown in Fig. 13. It has a peak at the
wavelength around 470 nm and has broad tails.
The light from the halogen lamp was injected into

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S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

one end of the sample clear fiber, and the lightintensity was measured at the other end by a spectrum analyzer at wavelengths of 500 and 670 nm.
The fibers were then shortened to 3 m, and the lighttransmission was measured again. We calculated
the attenuation length j at a wavelength using theresults obtained from the two fibers with the twodifferent lengths as follows:
I "Ae\H,
I "Ae\H,
I
Ae\H""e\H,I
Ae\H

12
,
(3)
j"!
ln(I /I ) 
where A is a constant, I and I are the measuredlight intensities of the 15 m long and the 3 m longfibers, respectively. We obtained the average attenuation lengths of the clear fibers to be 9.3 m ata wavelength of 500 nm and to be 21.4 m ata wavelength of 670 nm and their variations to be
21% and 11%, respectively (see Fig. 14). By an
interpolation of the two results obtained for the
wavelengths of 500 and 670 nm, the attenuation

length at 550 nm, which corresponds to thewavelength of light from WLS fibers, was estimatedto be 12.9 m with the rms variation of 14%. These
results satisfy our requirements.
4.2.3. Light yield of WLS fibers
We sampled a 75 cm long fiber out of every 50 mlong WLS fiber in the fiber production. We measured the light yield of the sample WLS fibers using
the experimental setup shown in Fig. 15. We inserted a sample WLS fiber in a standard scintillating tile (120 mm;120 mm;4 mm) and measured
the light yield with the sample fiber with a PMT.
We required the average light yield to be more than
12 pes and its variation to be less than 3% in thismeasurement.
The distribution of the light yield is shown in
Fig. 16. The average light yield of the sample WLS

Fig. 15. Experimental setup for the light yield measurement of
WLS fibers.

Fig. 14. Distributions of the attenuation length of clear fibers at
wavelength of 670 nm (top) and at 500 nm (bottom).

Fig. 16. A distribution of the light yield of WLS fibers.

S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61
Table 4
The results of the light yield measurement of the WLS fibers

Ave. light yield (pes)
Variation (%)

ResultRequirement

12.2
2.9

'12
(3

57

Table 6
Order

Tile

Fiber

Light yield

0)iReference)
Reference
Sample (i)Reference
Sample (i#1)
Reference)

Standard)
Standard
Standard
Standard
Standard
Standard
)

r

)
r
G
s
G
r
G>
s
G>
r
G>
)

i#1

fibers and the rms variation were measured to be
12.2 pes and 2.9%, which satisfy our requirements.
We summarize the results in Table 4.
4.3. Tile fabrication
The scintillator plate was first cut into tiles withdimensions somewhat oversizing the required dimensions. We then performed fine cutting, carving
the fiber groove, and painting white the four tile
sides. After the tile fabrication, we sampled about
2% of the total in order to measure the response
variation. We sampled tiles according to Table 5,
the tile numbers being shown in Fig. 2. We sampled
eight 15° units each from layers 6, 12 and 23, andone 15° unit each from other layers. From each of
the sampled 15° units we sampled 12 tiles for layers
1 to 15 and 11 tiles for layers 16—23. In total,
513 tiles corresponding to 2.2% of the total were
sampled.
We require the light yield to be greater than 3 pes
per MIP for the tile/fiber with a WLS to clear fiber
splicing and two fiber-to-fiber connectors including
the attenuation in the fibers as mentioned in Section 2.
The experimental setup for testing the light yieldof the tile is almost the same as one used for the testi#2)of the WLS fibers (see Fig. 15). For this measurement, we prepared a set of standard WLS fibers(typically 60 cm long). The length of the standard
fibers was about 30 cm longer than the nominal
length, which induces an extra light attenuation.
Light from the standard WLS fiber embedded in
the sample tile was directly read out with a PMT(H1161GS); there were no clear fibers nor fiber-tofiber connections. An EM shutter installed between
the PMT and the WLS fiber makes an air gap
which attenuates the light intensity. Under the
given conditions of the measurement, our requirements correspond in this system to the light yield tobe more than 12 pes and the variation of the lightyield to be less than 2% after subtracting the variations due to non-uniformity of the concentrationof the wavelength shifter and the thickness ofsample tiles.
The variation of quality of standard fibers wascorrected using a reference tile. We monitored thelight yield of a standard fiber with the reference tile
before and after the measurement with a sample
tile. We measured the light yield of sample tiles andthe reference tile as shown in Table 6.

Table 5
List of tiles sampled in this test. We sampled 513 tiles in total. Note that a 15° unit in the layers from 1 to 15 (16 to 23) consists of 20 (18)
scintillating tiles
Layer no.

No. of units/layer

Tile no. sampled in a unit

No. of tiles

6, 12
23
1—5, 7—11, 13—15
16—22

8
8
1
1

1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20
1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18
1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20
1, 2, 3, 4, 6, 8, 10, 12, 14, 16, 18

192
88
156
77
total 513 (2.2%)

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S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

Each measurement was performed after checking
the quality of the standard fiber using the reference
tile. We use a ratiosGR,
G (r #r )/2
G
G>

(4)

as a measure of the relative light yield of the sample
tile, where s (r ) is the light yield of sample tile i (theG Greference tile) with a standard fiber. When the lightyield of a standard fiber with the reference tile
became lower than a given threshold, we replaced
the fiber with another. Once we define the absolute
light yield using the reference tile with the standard
fiber r , we can estimate the absolute light yields  of sample tile i as follows:Gs "r ;R .
(5)
G

G
The variation of the light yield of sample tiles wasmeasured to be 3.0%. The measured variation includes (i) the variation of the tile thickness (1.6%),(ii) the variation due to the non-uniformity of the
wavelength shifter concentration (1.7%), and (iii)the variation due to the uncertainty of the measurement (1.0%) in addition to the variation of the tile
fabrication. By subtracting these numbers from themeasured variation one can estimate the variationthat comes from the tile fabrication. We summarize
the minimum light yield and the light yield variation of the sample tiles in Table 7. These results
satisfy our requirement.
4.4. Fiber fabrication
One end of the WLS fiber is mirrored by aluminum sputtering with a cover of MgF , and theother end is spliced to a clear fiber by a thermal
fusion method. In order to check the quality of

Table 7
Summary of the light yield test results after the tile fabrication

Minimum light yield (pes)
Variation (%)
Extracted variation (%)

ResultRequirement

15
3.0
1.6

'12
—
(2

Fig. 17. Experimental setup for the light yield measurement
after fiber splicing.

mirroring and splicing, we measured light yield of
WLS fibers after these fabrication. In this test we
required the variation of the light yield should beless than 5% in rms. We also rejected the fibers ofwhich light yield is greater or less than the average
light yield by $10%.
We show the experimental setup in Fig. 17. We
use a UV lamp in a small dark box as a light source
and a PMT R580-17 (Hamamatsu) as a current
readout device. The light from the UV lamp wascollimated. We use a reference clear fiber to monitor the light intensity and the PMT gain. The lightintensities from the two fibers were measured witha picoamperemeter, and we used a ratio of themeasured currents for the sample fiber and thereference fiber as a measure of the relative lightintensity of the sample fiber. Fig. 18 shows the
distribution of the relative light yield. We obtained
the light yield variation of 4.4% in rms. Fibers
corresponding to 1.4% of the total had light yieldoutside the specification and were rejected.

S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

59

Fig. 18. A distribution of the light yield variation of WLS fibers
spliced to clear fibers.

4.5. Tile/fiber sub-assembly
We made 15° units with scintillating tiles and
WLS fibers spliced to clear fibers that passed ourquality tests. In total, 1196 units were produced. Asa final quality test, we sampled about 3% of theunits and measured the light yield and light leakage
to the adjacent tiles within a 15° unit using a b-ray
source. We sampled eleven 15° units from the 12thlayer and one 15° unit from each of the other layers.
The following are our final requirements on thequality for 15° units:
1. light yield of tile/fiber’s in 15° units with clear
fibers and mass connectors '3 pes,
2. response variation of tile/fiber’s with the same
size (10% in RMS,
3. response variation of tile/fiber’s within a tower(30% ((10% in RMS), and
4. a total of light leakage from a tile to the adjacenttiles (3.5%.
The system used in this test is shown in Fig. 19.
A 15° unit is mounted on a table. A b-ray source(Sr) with a lead collimator of 5 mm in diameterand a trigger counter are attached to an arm bar.
The source and the trigger counter scan the sample
15° unit, and the light yield of each tile/fiber is
automatically measured. As mentioned in Section 2, a 15° unit consists of 18 (or 20) tile/fiber’s.
We grouped 18 (or 20) readout optical fibers into
four and read out with 4 PMTs (Hamamatsu
H1161GS). The assignment of the tile/fiber’s to theFig. 19. The automatic scanning system for the light yieldmeasurement of 15° units.
Table 8The assignment of tiles in a 15° unit to the four PMTs
PMT number

Tile number

PMT (1)
PMT (2)
PMT (3)
PMT (4)

1, 5, 9, 13, 17
2, 6, 10, 14, 18
3, 7, 11, 15 (19)4, 8, 12, 16 (20)four PMT’s is given in Table 8. The uncertainty of
the light yield measurement with this system is about
3.0%. We measured the light yield of total lightleakage using the four PMT’s at once. When we test
tile 14 with PMT(2), we also measure the light yieldfrom the tiles 11, 12, 13, 15, and 16, which are all
adjacent to the seed tile (tile 14), with the other
PMT’s, PMT(1), (3), (4). The total light leakage
from the seed tile to the adjacent tiles is defined by
X(11)#X(12)#X(13)#X(15)#X(16)L(14)(%),
X(14)
;100,

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S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

Table 9Results of the quality test of 15° units
Measurement

ResultRequirement

Light yield (pes)Average
Minimum

7.7
5.5

—
'3

Variation (%)
Within a tower
With the same sizes

7.9
6.4

(10
(10

Light leakage (%)
Average
Maximum

1.1
2.8

—
(3.5

Fig. 21. The response variation of tiles with the same sizes,
except for tiles 1, 19, 20.

Fig. 20. The response variation within a tower.

where L(14) is the total light leakage of tile 14 to
the adjacent tiles and X(n) is the light yield of tile n.
We summarize the results of these measurements
in Table 9. The average light yield of tile/fiber’s wasmeasured to be 7.7 pes, and all tile/fiber’s satisfied
the required light yield larger than 3 pes. Distributions of (i) relative deviation of response of tiles
within a tower from the average response and (ii)relative deviation of response of tiles with the same
sizes from the average response are shown in

Fig. 22. A distribution of the total light-leakage from a tile tothe adjacent tiles within a 15° unit.

Figs. 20 and 21, respectively. Light yield variationof tiles within a tower was measured to be 7.9%.
Light yield variation of tiles with the same sizes wasmeasured to be 6.4%. This result is consistent with

S. Aota et al. /Nucl. Instr. and Meth. in Phys. Res. A 420 (1999) 48—61

61

We finally show the average light yield of tiles
against their production order in Fig. 23. We do
not see any significant dependence of light yield on
the production order.

5. Conclusion
We performed the quality tests for the CDF
plug EM tile/fiber calorimeter at a number ofmajor points in the production. We checked thequality of scintillating tiles and optical fibers to
select them satisfying our requirements. We finallysampled 33 of 15° units and checked their
quality. We confirmed that all of the sampled units
satisfy our requirements. After the production, allof 15° units were tested using cosmic rays in
1995—1996.
Fig. 23. The average light yield dependence on the production
order. No significant dependence was observed.

what we expect from variations of scintillating tiles(2.8%), optical fibers (4.4%), and reproducibility ofthe measurement (3.0%). These results satisfied ourrequirements. Shown in Fig. 22 is the distributionof the measured light leakage. We measured theaverage light leakage to be 1.1%, and all tile/fiber’ssatisfied our requirement on the light leakage to beless than 3.5%.

References[1] CDF collaboration, CDF Plug Upgrade Technical Design
Report, 1992, p. 14.
[2] CDF collaboration, CDF II Technical Design Report, 1996,
p. 9-1.
[3] T. Asakawa et al., Nucl. Instr. and Meth. A 340 (1994)
458.
[4] S. Aota et al., Nucl. Instr. and Meth. A 352 (1995) 557.
[5] S. Kim, Nucl. Instr. and Meth. A 360 (1995) 206.
[6] K. Hara et al., Nucl. Instr. and Meth. A 348 (1994) 139.
[7] K. Hara et al., Nucl. Instr. and Meth. A 373 (1996) 347.