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Construction of a cylindrical MWPC for the central tracking detector of H1
Nuclear Physics B (Proc. Suppl .) 16 (1990) 518-519 North-Holland
518
CONSTRUCTION OF A CYLINDRICAL MM -FOR*THE CENTRAL TRACKING DETECTOR OF Hl . G . BERTRAND-COREMANS ., A . DE ROECK ( +) , J .P . DEWULF, E . EVRARD, P . HUET ( ), D . JOHNSON, P . MARAGE, J . MOREELS, R . ROOSEN, G . VAN BEEK Presented by P . MARAGE IIHE (ULB-VUB), Pleinlaan 2, B-1050 Brussels, Belgium
A set of two cylindrical multiwire proportional chambers, 2 .2 meter long and 1 meter in diameter, are being built as part of the central tracking detector of the H1 experiment, at HERA . The chamber bodies are of sandwich type ; the cathodes are segmented in pads . The transmission line, which is part of the sandwich, has an impedance matched to the preamplifiers . The electronic readout has been tested on a flat prototype chamber ; the time resolution is well below the 96 ns bunch crossing time at HERA . Four Sets of MWPC's will be part of the
The 25 pm thick, 90 cm large aluminium
tracking detector of H1
foil is wound in a helix form on a precision
- 3 planar chambers in the forward (wrt . the
steel mandril (cylindricity better than 50 um)
proton direction) and in the backward regions ;
982 mm in diameter, 2 .60 m long and weighting
- 2 double layers of cylindrical chambers in
2 tons . An underpressure within the mandril,
the central region, with diameters of about
transmitted through hole, allows sucking,
30 cm and about 1 m .
keeping in place and gluing the various layers
The main goals of these chambers are
of materials .
1 . the determination of the interaction time,
Three Rohacell plates (raw dimensions
with a resolution better than the HERA bunch
250 x 125 cm2 , 5 mm thick) are glued on the
crossing time ;
alumiriium foil . The plates have previously
2 . to allow for a fast vertex reconstruction,
been dehumidified, aged and preformed for 24
at the first level trigger, to .reduce the high
hours at 160°C and for 30 min at 180°C in an
background rates, especially the beam-gas
airpulsed oven .
and beam-wall interactions ;
The Rohacell surface is then milled on a
3 . the linking of the tracks with the tower
lathe, down to the required thickness of 4
structure of the liquid argon calorimeter .
mm . An external aluminium foil, which ser-
Goals 1 and 2 require fast electron drift and fast electronics ; goals 2 and 3 impose a defined pad structure . In addition, the amount of detector material has been reduced to a minimum . The inner body of the inner chamber is made of an aluminium - Rohacell - aluminium sandwich .
ves as cathode for the inner chamber, is glued on the Rohacell . The outher body of the inner chamber, which also supports the inner cathode of the outer chamber, has a more complicated structure . Kapton foils 25 pm thick, 110 cm large are covered on one face with a thin and uniform
(+) Universitaire Instelling Antwerpen, Wilrijk, Belgium Aspirant MRS, Belgium
M
0920-5632/90/$3 .50 @ Elsevier Science Publishers B.V . North-Holland
G. Bertrand-Coremans et al./ Construction ofa cylindrical MWPC layer of graphite ink, using the screen-printing technique . The ink is polymerised at 120°C for 1 hour . The resistivity is reasonably uniform around the choosen value of 200 kO per square, reducing the cross talk between pads to a few percent .
519
The chamber ends are reinforced by Vetronite flanges, wich 1.
fix the 8 mm gas gap ;
2 . support the high voltage alimentation and the 1600 anode wires of each chamber (20 ;rm Tungsten wires, under 60 g mechanical ten-
The kapton foil is placed in helix on a second steel mandril (diameter 1006 mm) . The graphite side serves as outer cathode for the
sion, pitch of 2 mm, supported in addition by two intermediate flanges) ; 3 . support the gas distribution system ;
inner chamber . On the outer kapton surface are
4 . support the preamplifiers and readout
glued 11 x 19 cm2 pads made of 25 Nm kapton
electronic cards .
foils covered with 1 ;rm copper . The complete
A flat prototype chamber has been built . It
pad system of the chamber is made of 18 pads
has a full chamber length and corresponds to
along the beam axis and 16 0 sectors . Roha-
one ~ sector ; it is equipped with 100 anode wi-
cell plates are glued, and machined down to a
res and 18 pads of differing types and dimen-
thickness of 3 mm .
sions . The aim was to test several details of
On each pad, a 50 pm in diameter copper
the construction scheme, especially the influ-
wire is glued with conductive glue . The wi-
ence of the pad size and capacity, and the
res pass through the Rohacell thanks to ho-
response of the readout line as incorporated in
les made in the plates before gluing . The,
the sandwich .
run on the Rohacell surface, parallel to the
The prototype has been tested with a nix of
beam axis, towards one end of the chamber,
50 7. Ar + 50 9 C 2H 6 + 0 .2 7 Freon . At 98 % ef-
where they transnit the signal to the pream-
ficiency, a plateau width of 200 V is obtained
plifiers .
at 2 .9 kV . No significant influence of the pad
The impedance of the transmission line is
type is observed . The quality of the signal is
matched to the preamplifiers thanks to a ground
satisfactory . The time resolution is about 60
plane made of kapton + copper foils (60 cm
ns, well below the 96 ns bunch crossing time .
large, 220 cm long, 25 pm kapton,
1 pm cop-
per), glued on the Rohacell surface which supports the wires . The structure is completed by an external 2 mm thick Rohacell layer, covered with an external aluminium foil which serves as a cathode for the outer chamber . The outer structure of the outer chamber is similar to this .
E E
ACKNOWLEDGEMENTS . It is a pleasure to thank our colleagues in Türich, and especially M .N . Lordong at SIN for their help and support .
Cross section of the endstructure
518
CONSTRUCTION OF A CYLINDRICAL MM -FOR*THE CENTRAL TRACKING DETECTOR OF Hl . G . BERTRAND-COREMANS ., A . DE ROECK ( +) , J .P . DEWULF, E . EVRARD, P . HUET ( ), D . JOHNSON, P . MARAGE, J . MOREELS, R . ROOSEN, G . VAN BEEK Presented by P . MARAGE IIHE (ULB-VUB), Pleinlaan 2, B-1050 Brussels, Belgium
A set of two cylindrical multiwire proportional chambers, 2 .2 meter long and 1 meter in diameter, are being built as part of the central tracking detector of the H1 experiment, at HERA . The chamber bodies are of sandwich type ; the cathodes are segmented in pads . The transmission line, which is part of the sandwich, has an impedance matched to the preamplifiers . The electronic readout has been tested on a flat prototype chamber ; the time resolution is well below the 96 ns bunch crossing time at HERA . Four Sets of MWPC's will be part of the
The 25 pm thick, 90 cm large aluminium
tracking detector of H1
foil is wound in a helix form on a precision
- 3 planar chambers in the forward (wrt . the
steel mandril (cylindricity better than 50 um)
proton direction) and in the backward regions ;
982 mm in diameter, 2 .60 m long and weighting
- 2 double layers of cylindrical chambers in
2 tons . An underpressure within the mandril,
the central region, with diameters of about
transmitted through hole, allows sucking,
30 cm and about 1 m .
keeping in place and gluing the various layers
The main goals of these chambers are
of materials .
1 . the determination of the interaction time,
Three Rohacell plates (raw dimensions
with a resolution better than the HERA bunch
250 x 125 cm2 , 5 mm thick) are glued on the
crossing time ;
alumiriium foil . The plates have previously
2 . to allow for a fast vertex reconstruction,
been dehumidified, aged and preformed for 24
at the first level trigger, to .reduce the high
hours at 160°C and for 30 min at 180°C in an
background rates, especially the beam-gas
airpulsed oven .
and beam-wall interactions ;
The Rohacell surface is then milled on a
3 . the linking of the tracks with the tower
lathe, down to the required thickness of 4
structure of the liquid argon calorimeter .
mm . An external aluminium foil, which ser-
Goals 1 and 2 require fast electron drift and fast electronics ; goals 2 and 3 impose a defined pad structure . In addition, the amount of detector material has been reduced to a minimum . The inner body of the inner chamber is made of an aluminium - Rohacell - aluminium sandwich .
ves as cathode for the inner chamber, is glued on the Rohacell . The outher body of the inner chamber, which also supports the inner cathode of the outer chamber, has a more complicated structure . Kapton foils 25 pm thick, 110 cm large are covered on one face with a thin and uniform
(+) Universitaire Instelling Antwerpen, Wilrijk, Belgium Aspirant MRS, Belgium
M
0920-5632/90/$3 .50 @ Elsevier Science Publishers B.V . North-Holland
G. Bertrand-Coremans et al./ Construction ofa cylindrical MWPC layer of graphite ink, using the screen-printing technique . The ink is polymerised at 120°C for 1 hour . The resistivity is reasonably uniform around the choosen value of 200 kO per square, reducing the cross talk between pads to a few percent .
519
The chamber ends are reinforced by Vetronite flanges, wich 1.
fix the 8 mm gas gap ;
2 . support the high voltage alimentation and the 1600 anode wires of each chamber (20 ;rm Tungsten wires, under 60 g mechanical ten-
The kapton foil is placed in helix on a second steel mandril (diameter 1006 mm) . The graphite side serves as outer cathode for the
sion, pitch of 2 mm, supported in addition by two intermediate flanges) ; 3 . support the gas distribution system ;
inner chamber . On the outer kapton surface are
4 . support the preamplifiers and readout
glued 11 x 19 cm2 pads made of 25 Nm kapton
electronic cards .
foils covered with 1 ;rm copper . The complete
A flat prototype chamber has been built . It
pad system of the chamber is made of 18 pads
has a full chamber length and corresponds to
along the beam axis and 16 0 sectors . Roha-
one ~ sector ; it is equipped with 100 anode wi-
cell plates are glued, and machined down to a
res and 18 pads of differing types and dimen-
thickness of 3 mm .
sions . The aim was to test several details of
On each pad, a 50 pm in diameter copper
the construction scheme, especially the influ-
wire is glued with conductive glue . The wi-
ence of the pad size and capacity, and the
res pass through the Rohacell thanks to ho-
response of the readout line as incorporated in
les made in the plates before gluing . The,
the sandwich .
run on the Rohacell surface, parallel to the
The prototype has been tested with a nix of
beam axis, towards one end of the chamber,
50 7. Ar + 50 9 C 2H 6 + 0 .2 7 Freon . At 98 % ef-
where they transnit the signal to the pream-
ficiency, a plateau width of 200 V is obtained
plifiers .
at 2 .9 kV . No significant influence of the pad
The impedance of the transmission line is
type is observed . The quality of the signal is
matched to the preamplifiers thanks to a ground
satisfactory . The time resolution is about 60
plane made of kapton + copper foils (60 cm
ns, well below the 96 ns bunch crossing time .
large, 220 cm long, 25 pm kapton,
1 pm cop-
per), glued on the Rohacell surface which supports the wires . The structure is completed by an external 2 mm thick Rohacell layer, covered with an external aluminium foil which serves as a cathode for the outer chamber . The outer structure of the outer chamber is similar to this .
E E
ACKNOWLEDGEMENTS . It is a pleasure to thank our colleagues in Türich, and especially M .N . Lordong at SIN for their help and support .
Cross section of the endstructure