The Small angle TIle Calorimeter (STIC) provided calorimetric coverage in
the very forward region of the DELPHI experiment at the LEP collider. The
major task of the calorimeter was to provide high precision luminosity
measurement by measuring with permill accuracy the Bhabha cross section.
The STIC was made up by two cylindrical detectors placed on either side of
the DELPHI interaction region and mounted around the beam pipe. The
detectors were 84 cm in diameter and 90 cm long. A tungsten shield
in front of the calorimeter provided a very sharp shadow which was used
to define with high precision the acceptance for Bhabha electrons.
The internal mechanical precision
of the detector had in addition to be better than 50 microns.
The detector was a sampling lead-scintillator calorimeter where the blue light
produced by the electromagnetic shower in the scintillator was carried to
the photodetectors at the back of the calorimeter by means of plastic
fibers doped with green wave length shifter. The fibers collected the light
over the whole depth of the calorimeter and were uniformly distributed over
the calorimeter cross section. In front of the calorimeters a set of scintillation
counters, called the veto counters, were used to separate electrons from photons.
Inside the calorimeters were two layers of
Si strip detectors which were used to measure the direction of the showers.
19,000 scintillator pieces with 490 different shapes were produced in
IHEP-Protvino for the detectors. They were individually machined from injection molded
scintillator plates with a very high precision. 800,000 holes had to be drilled
and punched in the scintillators and absorbers
to let the 8,000 fibers through. Because of the high mechanical precision
which was needed, all work was
done in a temperature controlled enviroment (21+-0.5 degrees).
The STIC project was a collaboration between 13 institutes from Italy,
Russia, Norway, Sweden, Portugal and CERN. A total of ca. 60 people was
involved in the project. The detector was installed in DELPHI in 1994
and I was the STIC project leader during 1996-2001.
One of the two STIC calorimeters is being tested before installation.
One of the 16 amplifier cards used to amplify the
signals from the Si Strip detectors. These cards sits on a ring-shaped printed
circuit board together with two so-called master-cards which are used for the
final 8 to 1 multiplexing of the Si strip signals from the amplifier cards
before they are sent to the Sirocco Flash ADCs in the countingroom.
The inside of one calorimeter module (a calorimeter
consists of two such modules). The sandwich
structure of the detector is clearly seen as well as the bundles of wavelength
shifting fibers going to the phototetrodes.
One half-layer of scintillators. The complete detectors consists of 47 lead-scintillator layers
and two Al-Si strip layers.
One of the two STIC calorimeters after it has been
installed around the beampipe in one of the end-caps of DELPHI. The white cables
in the lower right corner are fiberbundles for the Vetocounter.
Front-view of a STIC calorimeter. In the center of the
calorimeter is the hole for the beampipe. Around the hole is a ring of
electronics for the LED system and around the outer edge is a ring of
electronics for the Si Strip shower maximum detector.
A side-view of STIC showing the kapton cables which
takes the Si Strip signals out of the calorimeter and two MX4 fan-in cards used
for the first 120 to 1 multiplexing and for charge amplification.
A close-up of the wavelength shifting fibers and the
fiberholders which are attached to tetrodes in the finished detector.
A close up of a scintillator layer showing the tower
structure. Each calorimeter has 160 projective towers. There are several holes
for the fibers in each scintillator tower tile and in addition two holes used to
attach the tile with a very high precision to the lead plate.
The large veto scintillator before installation.
Close-up of the front showing the details of the LED
and Si Strip electronics.
One of the two Silicon Strip detector layers showing
the inner ring of Si Strip detectors. A complete layer has also an outer ring.
One of the Hamamatsu R2149 tetrodes used to read out
the light together with its preamplifier.
The small veto scintillator that was attached to the beampipe.
Responsible for the content of this page is
Vincent Hedberg
|
One of the two STIC calorimeters is being tested before installation. One of the 16 amplifier cards used to amplify the signals from the Si Strip detectors. These cards sits on a ring-shaped printed circuit board together with two so-called master-cards which are used for the final 8 to 1 multiplexing of the Si strip signals from the amplifier cards before they are sent to the Sirocco Flash ADCs in the countingroom. The inside of one calorimeter module (a calorimeter consists of two such modules). The sandwich structure of the detector is clearly seen as well as the bundles of wavelength shifting fibers going to the phototetrodes. One half-layer of scintillators. The complete detectors consists of 47 lead-scintillator layers and two Al-Si strip layers.  One of the two STIC calorimeters after it has been installed around the beampipe in one of the end-caps of DELPHI. The white cables in the lower right corner are fiberbundles for the Vetocounter. |
Front-view of a STIC calorimeter. In the center of the calorimeter is the hole for the beampipe. Around the hole is a ring of electronics for the LED system and around the outer edge is a ring of electronics for the Si Strip shower maximum detector. A side-view of STIC showing the kapton cables which takes the Si Strip signals out of the calorimeter and two MX4 fan-in cards used for the first 120 to 1 multiplexing and for charge amplification. A close-up of the wavelength shifting fibers and the fiberholders which are attached to tetrodes in the finished detector. A close up of a scintillator layer showing the tower structure. Each calorimeter has 160 projective towers. There are several holes for the fibers in each scintillator tower tile and in addition two holes used to attach the tile with a very high precision to the lead plate.  The large veto scintillator before installation. |
Close-up of the front showing the details of the LED and Si Strip electronics.  One of the two Silicon Strip detector layers showing the inner ring of Si Strip detectors. A complete layer has also an outer ring. One of the Hamamatsu R2149 tetrodes used to read out the light together with its preamplifier.  The small veto scintillator that was attached to the beampipe.  |
Responsible for the content of this page is Vincent Hedberg