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
