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WITH COSMIC. DATA OF THE WARM IRON CALORIMETER .... Iron Calorimeter built for SLD have been shown. ... *t**. +#. I. -2. 0. 2. 4. Fit residual. (cm) lb-. Fig. 6.
SLAC-PUB-5332 November 1990 (1)

STATUS AND PRELIMINARY DATA OF THE WARM

PERFORMANCE IRON CALORIMETER

SLD-WIC

WITH COSMIC IN SLD”

COLLABORATION

A. C. BENVENUTI INFN,

Sezione di Bologna, I-40126 Bologna, Italy

L. PIEMONTESE INFN,

Sezione di Ferrara and Universita

A. CALCATERRA,

di Ferrara,

I-44100 Ferrara,

R. DE SANGRO, P. DE SIMONE, and M. PICCOLO

Lab. Nazionali

di Frascati

delI’INFN,

I-00044

Italy

I. PERUZZI,’

Frascati,

Italy

P. N. BURROWS, W. BUSZA, S. L. CARTWRIGHT, S. FUESS, S. GONZALEZ, T. HANSL-KOZANECKA, A. LATH, T. LYONS, L. S. OSBORNE, L. ROSENSON, U. SCHNEEKLOTH, F. E. TAYLOR, R. VERDIER, D. C. WILLIAMS, and J. M. YAMARTINO Massachusetts

Institute

of Technology, Cambridge,

MA 02139, USA

N. BACCHETTA, INFN,

D. BISELLO, A. CASTRO, M. LORETI, L. PESCARA, and J. WYSS Sezione di Padova and Universitci di Padova, I-35100 Padova, Italy

B. ALPAT,

R. BATTISTON,

G. MANTOVANI, INFN, INFN,

and Universitci

R. CASTALDI,

Linear

di Perugia,

I-06100 Perugia,

Italy

and P. G. VERDINI

di Pisa, I-56010 S. Piero a Grado, Italy

J. ESCALERA, D. KHARAKH, and R. W. ZDARKO

Accelerator

R. DELL’ORSO,

and L. SERVOLI’

C. VANNINI,

Sezione di Pisa and Universita

B. L. BYERS, Stanford

M. PAULUZZI,

Sezione di Perugia

M. CARPINELLI,

G. M. BILEI,

Center, Stanford

University,

R. L. MESSNER, Stanford,

CA 94309, USA

J. R. JOHNSON University

of Wisconsin,

Presented

Madison,

WI 53706, USA

by A. Calcaterra

Invited paper presented at the Experimental Apparatus for High Energy Physics and Astrophysics, San Miniato, Italy, May 28-June * Work supported by Department of Energy contract DE-ACO3-76SFOO515. $ Also at Universitk di Perugia, I-06100 Perugia, Italy. 5 Present address: Universiti di Firenze, I-50125 Firenze, Italy.

1, 1990.

1. Introduction The SLD is an e+e- detector optimized tion at the Stanford (WIC)

Linear Accelerator

is a device built using limited

and has a double purpose: caping from the Liquid

for 2’ physics, and is approaching

Center (SLAC).

The Warm Iron Calorimeter

streamer tubes to instrument

the magnet yoke,

it will measure the energy of tails of hadronic

Argon Calorimeter

(the main instrument

and the coil, and it will also be used as a muon identifier The design choices, construction

comple-

showers es-

of SLD calorimetry)

and tracker.

details, and expected performance

have already

been described elsewhere.’ In this note, we report on the present status of the WIC, and show some preliminary

results obtained

2. Overall . The WIC mixture

tubes are operated

system

modules

disconnected

strained

during

with

of 4.75 kV

(the nonflammable

operation,

there are 165 disconnected

a total of N 8600 streamer tubes.

not to work properly.

due to different

mechanical

tubes

This figure includes

because of gas leaks, as well as modules

installation,

gas

is being used2).

After about 1000 hours of continuous compared

integrity

at a voltage

88%COz-9.5%iC4Hls-2.5%Ar

in the WIC,

from cosmic ray data.

which

mounting,

have been

and are known

Most of the tubes which failed to hold HV did so during the

first few hours after turn-on. The WIC

electronics3

and - 9000 calorimetric

is designed to acquire data from towers.

channel boards,4 supervised

The readout is actuated

90000 strip

channels

for the strips via 3000 32-

by 42 controllers/multiplexers5

and 6 FASTBUS

custom

modules.6 For the pad readout, 7 the signals from 64 VME

cards, housing the preamplifier

are read out serially functions.

towers are sent via shielded

hybrids

under the control of 16 VME

The number

of problem

and sample-and-hold cards containing

channels in the detector 2

cable to

devices, and

ADCs and timing

is below the 1% level;

most

of these

are due to hardware

shorts

to ground,

or towers

shorted

together,

and

can easily be recovered.

3. Trigger The WIC is a self-triggering discriminators

digital

and compared a “modular”

to other boards in a physical

to a (programmable) intelligent

trigger,

by requesting, A typical

(CLU)8:

minimum

These modular a FASTBUS

usually requiring

as a trigger. illuminate

Different the detector

triggers

cards,

layers, to build

of requesting

are finally

specific

combined

into

any combination

of digital

ORs from

is the request of two tracks in opposite octants?

Up until now, several hundred thousand WIC,

of triggered

The

module which generates an SLD-wide

under software control, trigger

number

and

layer of chambers.

which also has the capability

noisy ones.

the Cosmic Logic Unit

the detector.

of the onboard common threshold

ORs from separate layers are then added in the controller

layers, and ignoring

trigger,

device: the outputs

are added to give a fast OR of the 32 channels of each board,

this OR can be daisy-chained individual

and data taking

cosmic muons have been recorded in the

the coincidence of diametrically combinations as uniformly

of octants as possible.

opposed octants of the barrel

have been used, in such a way as to A characteristic

event is shown in

Fig. 1. WIC

triggers are routinely

for calibration

and diagnostic

used by other SLD subsystems to collect cosmic rays, purposes.

A special (“pointing”)

veloped, using four special layers in each octant, the beam direction, of the detector: of the Central

with

was used to obtain

was also de-

strips transverse

in order to trigger on cosmic muons passing through

this type of trigger Drift

equipped

trigger

to

the center

tracks useful for calibration

Chamber.

o The CLU was not yet implemented at the time this report was given, and in its place a normal fast coincidence, gated with the beam crossing signal, was used. The CLU has been installed since then, and found to perform according to specifications.

4. Preliminary The behavior performance,

performance

of the WIC

are extensively

the two lego-plots

of the detector

as a calorimeter,

as well as preliminary

reported in Ref. 7. One typical

refer to the twofold

results of its

event is shown in Fig. 2:

segmentation

in depth of the WIC towers, and

the two axes of each plot (4 and 19channel number)

cover the entire solid angle. The

two peaks correspond pulse heights

is given, with

were not corrected

efficiency

tracks, as a function

subtracted.

of

In both Figs. 2 and 3, the data

and average cluster size have been studied,

of the threshold

on the strip discriminators.

is stable over the whole range of thresholds with

using muon

Figure 4 shows that

from 2 to 8 mV. The average

expectations

from

earlier

measurements,

into account the dead zones between chambers in the same layer. The average

cluster

size decreases smoothly

with

increasing

point is at 2-3 mV. In fact, while efficiency thresholds “normal”

threshold,

S-strips clusters becomes higher, affecting can also be plotted

muon on the chamber. projected

expectations, orthogonal

raising the strips to the

of the angle of impact

of the

axis represents this angle (in absolute It can be seen, according

to

that the effect of dead regions between chambers is more relevant

for

to the wires.

crossing.

A preliminary

measurement

is given in Fig. 6, in which

of the spatial resolution

we plot the difference

one layer, and its expected position The central part has been fitted due to low-momentum scattering,

two consecutive

setting

adversely the resolution.

as a function

In Fig. 5, the horizontal

in a plane orthogonal

and the optimal

does not decrease appreciably

beyond this level, the rate of clusters with

The efficiency

value),

In Fig. 3, a distribution

effects.

value of 85% is in good agreement taking

and exit points.

pedestals

for geometric

The single-layer

the efficiency

to the entrance

obtainable

between

from WIC

the measured

strips

point

(from a fit of all other layers to a straight

in

line).

to a Gaussian having g = 4.4 mm, and the tails are

muons, the trajectories

of which are more affected by multiple

and more bent by the magnetic field in the iron. No cut has been made on

the x2 from the track fit. Work on software alignment 4

of chambers is still in progress,

and data taking

with field both on and off will help to reach the design resolution

in

the near future.

5. Conclusions Some preliminary Iron Calorimeter the capabilities

results from analysis of cosmic ray data taken using the Warm

built

for SLD have been shown. These results already

of the WIC

muon identification

to operate

and tracking

as expected,

both as a calorimeter

device.

References 1. G. Callegari

et al., SLAC-PUB-4461,

October

1987;

A. C. Benvenuti

et al., Nucl. Instr.

and Meth.

A276 (1989) 94;

A. C. Benvenuti

et al., Nucl. Instr.

and Meth.

A289 (1990) 463.

2. S. Cartwright

et al., Nucl. Instr.

and Meth.

A277 (1989) 269;

A. C. Benvenuti

et al., Nucl. Instr.

and Meth.

A284 (1989) 339;

A. C. Benvenuti

et al., Nucl. Instr.

and Meth.

A290 (1990) 353;

A. Calcaterra

et al., Nucl. Instr.

3. A. C. Benvenuti F. Beconcini

and Meth.

et al., Nucl. Instr.

et al., Nucl. Instr.

A289 (1990) 449.

and Meth.

and Meth.

A289 (1990) 577;

A277 (1989) 222.

4. See Ref. 3, and references therein. 5. N. Bacchetta

et al., IEEE

6. G. M. Bilei et al., IEEE 7. P. N. Burrows 8. See contribution

Trans. Nucl. Sci. NS-36 (1989) 1657. Trans. on Nucl. Sci. NS-35

et al., SLAC-PUB-5305, by M. Carpinelli,

August

demonstrate

(1988) 282.

1990.

in these proceedings.

and as a

Figure 1. A representative 2. A typical

WIC

event as seen by the WIC

cosmic muon in the WIC calorimetry

3. Distribution 4. Variation

cosmic-ray

Captions

of pedestal-subtracted with discriminator

strips.

towers.

pulse height for WIC

threshold

of efficiency

towers.

and average cluster size for

strips.

5. Efficiency 6. Distribution

of WIC

chambers as a function

of crossing angle.

of fit residuals for cosmic muons.

Run Number

- South

936

Side

Event

Looklnq

Fig. 1

North

5153

Seq

5152

WIG

1

ONE EVENT

- 1.5 & 1.0 E .5 z .o

WIG

2

ONE EVENT

Fig. 2

60

0" 8-90

0

200

400

Charge

(PC)

Fig. 3

600 6691A12

q

1.00 -

0

Efficiency

0

Cluster

size (right

scale)

q

q

0.80"""""""' 0

2

Threshold

I " 6

4

Voltage

(mV)

Fig. 4

"

I '1 8

"1 10°

1.2

1.0 I I I I

-L-

.8

.2

.O 10 Phi

angle( degrees)

Fig. 5

x10 8.

3

I

I

I

I

6.

4.

2.

0.

+#

*t**

I

-2 Fit

0 residual

lb-

2 (cm)

Fig. 6

4