EMCal ALICE modules stacking / assembly
User’s Manual / Tutorial

Manoel Dialinas

updated 25.01.08

1. Put assembly fixture dust clean, and all surfaces degreased.

2. Check guide rods system (guiding rods Ø 1.30 mm) below the table, and start to riseup them.

3. Mount stop system on the table

4. Mount the two Ø6 locating pins on the center block, for the FrontPlate, on theassembly tooling.
5. Front plate : drawing 26K200_E, locate Phi and Eta sides, check outer sizes (mainly
width in Phi direction) and thickness of the edge for strap,
6. Compression Plate : locate Phi and Eta sides, check outer sizes (drawing 26K202_E)
7. Back Plate : drawing 26K201_E, locate Phi and Eta sides, check geometricaldimensions (mainly width in Phi direction), check that the 5 M6x1 screws for set up of
Belleville Washers turn free in threaded holes.
8. Strap : drawing 26K203_C, check on a template distance between flanges (281.2±0.1 mm), check overall thickness of straps is < 3.15 mm, including welding.

9. Mount FrontPlate on the center block first, check Phi and Eta sides, rise up the guiding
rods in order to locate the first Bond Paper.

10. Check height of 4 towers of 77 scintillators. If total height is different at corners, makedecision to shim.

11. Start stacking. Put one Bond paper first (drawing 26K206_B)), then Scintillator(drawing 26K205_A), then Bond Paper, then lead tile, and so on... Rise up
progressively guiding rods for each layer. One operator for handling lead and bondpaper, one other for handling scintillator10. Stack 77 layers, finish with a Bond Paper.

11. Put 5 sets (one set = 8 stacks of 2 washers) of Belleville washers into the 5 Ø 8 mm
holes of Compression Plate, mount Belleville Washers plunger on the Belleville
washers stacks.
12. Mount Compression Plate on stacked module, check Phi and Eta sides before
mounting.

13. Mount BackPlate on module, check Phi and Eta sides before mounting.

14. Mount load cells block on Back Plate, put the 5 fastening screws

15. Put bridge on rod bars

16. Tight bridge on rod bars, check top, bottom, left and right sides of stacked module
17. Remove lateral stops
18. Start to load the load cells. Put load at corners first (one corner, then opposite corner)and finish at center. During this step Compression Plate will move down andcompression load will remain at zero (or low values). Once most of flatness defaults oflead tiles are removed, Compression Plate no more shift down and compression load
start to rise.

19. Mount black paper shroud on 4 lateral sides of the module.
20. Cut pockets in the black paper shroud in order to be able to put flange straps into
pockets of Back Plate and Front Plate.
21. Mount straps, low flange first, check that there is a correct contact between edges offlanges and edges of Front Plate and Back Plate, then put the 24 M2.5 screws without
tighting them, just in order to make sure that strap flanges are in good contact withedges of Front Plate and Back Plate.

22. Set load cells at a medium value (40 kgf-88 lbs), wait 5 minutes for equilibrium ofload in the 5 sets, then tight the M2.5 screws with a torque of xxN.m

23. Set load cells at high value (64 kgf-140 lbs) in order to achieve the load for thecompression time of the module. Then remove bridge of Assembly Tooling in order tobe able to move the module.

24. Move down guiding rods.
25. Move module to compression place. Compression area need to be temperature
controlled.

26. Check geometrical squareness of Phi sides, and outer dimensions of module.
27. If not correct, call “Chief” in order to know what to do (move back to assembly
tooling for dismount-remount or store it ?).
28. During compression time each 2 hours, check shortening effect of module undercompression with indications of load cells (if the module shortens, compression loaddecreases). Set up back compression load at 80 kgf – 176 lbs if the module shortened.
29. After 3 days compression time, set compression load at nominal value : 28 kgf-62 lbs
for each load cell.
Compression time is achieved when load cell indication is quite stable.
Check and record temperature (< 22°C). Take care of temperature in assembly area atthis time, taking into account relationship between module and temperature :If ΔT 1°C→
ΔL strap
5.1 µ
If ΔT 1°C→
ΔL module 22+90+2=11.3 µ
If temperature in L3 is higher than temperature in assembly area by 1°C, increase ofmodule length will be 11.3 µ, as increase of strap length will be only 5.1 µ,compression load will rise during life time.
At the opposite, if temperature in L3 is lower than temperature in assembly area
compression load will decrease during life time.
30. Put loctite glue (n° 243) on threads of M6 plunger screws, put them in their threadedholes. Then tight plunger screws for Belleville washers progressively (process by ½
turn on each M6 plunger screw, total ≈1.75 turns) in order to transfert progressively
load from cells to Belleville Washers, at 1.75 turns load cells indication has to be zero(0),(crosscheck this information) the compression load in module is given by
Belleville Washers, no more by load cells. Check gap (nominal value 3 mm) between
Back Plate and Compression Plate using the Ø 7 mm inspection hole. Record thisvalue.

31. Remove load cells from compressed module, they can now be used for next module.

32. Put 24 Ø6 locating pins on the StripModule assembly tooling. They allow to achieve
location of modules with the 120 mm pitch.

33. Move module to Strip Module assembly table,

34. Locate Module using the Ø6 locating pins and Ø6 holes in Front Plate.

35. Mount 4 M5 studs (drawing 26K212_A) on Back Plate, use loctite glue (n° 243) tosecure studs in Back Plate,

36. Put optic fibers in each module.

37. Repeat 34 and 35 for 11 other modules
38. Put StrongBack on elevators. Locate at best position using studs and Bundle Fiberterminators.
39. Move down StrongBack until contact with BackPlates.

40.

41.

Tight the M5 nuts for studs with a torque of xx N.m (use a torquemeter for thisoperation).

42.

43. Close all holes (centering holes, guiding rods holes) with black paper on Front Plate,in order to avoid light enters in the module.

CERN-LHCC-2006-014
CERN/LHCC 96-32-Add3
15 April 2006

ALICE
The Electromagnetic Calorimeter
Addendum to theTechnical Proposal

Cover design by CERN Desktop Publishing Service.
Cover: Closeup photograph of fiber bundles out of two EMCal towers.
Printed at CERN
April 2006.
ISBN 92-9083-270-3
ISBN 978-92-9083-270-6

i

ALICE Collaboration
Alessandria, Italy, Facoltà di Scienze dell’Università and INFN:
P. Cortese, G. Dellacasa, L. Ramello and M. Sitta.
Aligarh, India, Physics Department, Aligarh Muslim University:
N. Ahmad, S. Ahmad, T. Ahmad, W. Bari, M. Irfan and M. Zafar.
Amsterdam, The Netherlands, National Institute for Nuclear and High Energy Physics (NIKHEF):
M. Botje, P.G. Kuijer and R. Snellings.
Athens, Greece, University of Athens, Physics Department:
A. Belogianni, P. Christakoglou1 , M. Fragkiadakis, P. Ganoti, A. Petridis, F. Roukoutakis 1 ,M. Spyropoulou-Stassinaki, C. Tagridis and M. Vassiliou.
Austin, USA, University of Texas† :G.W. Hoffmann, C. Markert31 , R.L. Ray and J.J. SchambachBari, Italy, Dipartimento di Fisica dell’Università and Sezione INFN:
G.E. Bruno, I.A. Cali, M. Caselle, G. D’Erasmo, D. Di Bari, D. Elia, R.A. Fini, A. Gallas, B. Ghidini,
E. Fiore, V. Lenti, V. Manzari, A. Mastroserio, F. Minafra, E. Nappi, F. Navach, A. Pantaleo, C. Pastore,
V. Paticchio, D. Perrino, F. Posa, R. Santoro, I. Sgura and G. Volpe.
Bari, Italy, Politecnico and Sezione INFN:
F. Corsi, D. De Venuto, U. Fratino, C. Marzocca and A. Tauro.
Beijing, China, China Institute of Atomic Energy:
X. Li, S. Lu, Z. Lu, B. Sa, J. Yuan, J. Zhou and S. Zhou
Bergen, Norway, Department of Physics and Technology, University of Bergen:
J. Alme, S. Bablok, A. Klovning, J. Nystrand, B. Pommeresche, M. Richter, D. Röhrich, K. Ullalandand H. Yang2 .
Bergen, Norway, Bergen University College, Faculty of Engineering:
H. Helstrup, K.F. Hetland, B. Kileng and K. Røed.
Berkeley, USA, Nuclear Science Division, Lawrence Berkeley National Laboratory † :S.-L. Blyth, H. Gray, M.J. Horner, P. Jacobs, S. Klein, G. Odyniec, J. Putschke, J. Rasson, H.G. Ritter,
I. Sakrejda, T.J.M. Symons and M. Van Leeuwen.
Bhubaneswar, India, Institute of Physics:
A.K. Dash, S. Dash, D.P. Mahapatra, S.C. Phatak, R. Sahoo and P.K. Sahu.
Birmingham, United Kingdom, School of Physics and Space Research, University of Birmingham:
L. Daniel, D. Evans, G.T. Jones, P. Jovanović, A. Jusko, J.B. Kinson, R. Platt, R. Lietava,
J.D. Tapia Takaki and O. Villalobos Baillie.

ii
Bologna, Italy, Dipartimento di Fisica dell’Università and Sezione INFN:
A. Alici, S. Antinori, P. Antonioli, S. Arcelli, G. Bari, M. Basile, G. Cara Romeo, L. Cifarelli,
F. Cindolo, D. Falchieri, A. Gabrielli, E. Gandolfi, D. Hatzifotiadou, G. Laurenti, M.L. Luvisetto,
A. Margotti, M. Masetti, R. Nania, F. Noferini, F. Palmonari, A. Pesci, R. Preghenella, G. Sartorelli,E. Scapparone, G. Scioli, G.P. Vacca, G. Venturi, M.C.S. Williams, C. Zampolli and A. Zichichi.
Bratislava, Slovakia, Comenius University, Faculty of Mathematics, Physics and Informatics:
V. Cerny, R. Janik, M. Pikna, P. Rosinsky, B. Sitar, P. Strmen and I. Szarka.
Bucharest, Romania, National Institute for Physics and Nuclear Engineering:
C. Aiftimiei, V. Catanescu, C.I. Legrand, M. Petrovici, A. Pop, C. Schiaua and V. Simion
Budapest, Hungary, KFKI Research Institute for Particle and Nuclear Physics, Hungarian Academyof Sciences:
G. Barnaföldi, L. Boldizsár, E. Dénes, Z. Fodor, E. Futó, T. Kiss, P. Lévai, G. Pálla, J. Sziklai, T. Tolyhi
and J. Zimányi.
Cagliari, Italy, Dipartimento di Fisica dell’Università and Sezione INFN:
I. Atanassov, C. Cicalo, A. De Falco, M. Floris, A. Masoni, D. Mura, G. Puddu, J. Samarati, S. Serci,
E. Siddi, G. Usai and H. Woehri.
Cape Town, South Africa, University of Cape Town:
J. Cleymans, G. de Vaux, R W. Fearick, A. Szostak and Z.Z. Vilakazi.
Catania, Italy, Dipartimento di Fisica dell’Università and Sezione INFN:
A. Badalà, R. Barbera, F. Blanco, F. Fichera, F. Librizzi, G. Lo Re, D. Nicotra, A. Palmeri,
G.S. Pappalardo, A. Pulvirenti, R. Rapicavoli, F. Riggi, G. Sacca and S. Urso.
CERN, Switzerland, European Organization for Nuclear Research:
G. Aglieri Rinella, G. Anelli, I. Augustin 4 , A. Augustinus, J. Baechler, P.L. Barberis 30 , J.A. Belikov5 ,L. Betev, A. Boccardi, R. Brun, M. Burns, P. Buncic 6 , I. Cali, R. Campagnolo, M. Campbell, F. Carena,
W. Carena, F. Carminati, G. De Cataldo 30 , S. Ceresa, S. Chapeland, C. Cheshkov, P. Chochula,P. Christiansen, A. Colla7 , J. Conrad, B.F. Correia Belbute, M. Davenport, J. de Groot, A. Di Mauro,
R. Divià, C. Engster, S. Evrard, C.W. Fabjan, L. Feng, D. Flierl, F. Formenti, U. Fuchs,
A. Garcı́a López, A. Gheata, M. Gheata 8 , C. González-Gutiérrez, R. Grosso 7 , C. Grigoras,
J.F. Grosse-Oetringhaus32 , R. Grosso7 , M. Gruwe, H.-A. Gustafsson9 , H. Hoedelmoser, P. Hristov,
M. Ivanov, L. Jirden, C. Jorgensen, A. Junique, S. Kapusta 10 , W. Kickinger, W. Klempt, A. Kluge,
F. Lackner, L. Leistam, J.P. Lo, M. López Noriega, C. Lourenço, I. Makhlyueva, J.C. Marin,
P. Martinengo, D. Meunier-Picard, M. Meoni 11 , M. Morel, A. Morsch, B. Mota, H. Muller, L. Musa,
T.K. Nayak12 P. Nilsson, D. Nouais13 , F. Osmic, B. Pastirčák10 , D. Perini, V. Peskov, R. Pestotnik,
A. Peters6 , V. Pinto Morais, S. Popescu, F. Rademakers, J.-P. Revol, P. Riedler, W. Riegler, P. Rosinsky,
H. Rovik, K. Šafařı́k, T. Schioler, K. Schossmaier, J. Schukraft, Y. Schutz 14 , P.A. Silva Loureiro,
C. Soos15 , G. Stefanini, D. Swoboda, M. Tadel, H. Taureg, M. Tavlet, P. Tissot-Daguette,
C. Torcato de Matos, H. Tydesjo, P. Vande Vyvre and J.-P. Vanuxem.
Csci/handigarh, India, Physics Department, Panjab University:
M.M. Aggarwal, A.K. Bhati, N. Kumar and L. Kumar
Clermont-Ferrand, France, Laboratoire de Physique Corpusculaire (LPC), IN2P3-CNRS andUniversité Blaise Pascal:
A. Baldit, V. Barret, N. Bastid, G. Blanchard, J. Castor, P. Crochet, F. Daudon, A. Devaux, P. Dupieux,
P. Force, S. Grigoryan16 , F. Guerin, R. Guernane, C. Insa, F. Jouve, J. Lecoq, F. Manso, P. Rosnet,
L. Royer, P. Saturnini and G. Savinel.

iii
Columbus, USA, Department of Physics, Ohio State University:
T.J. Humanic, I.V. Kotov, M.A. Lisa, B.S. Nilsen and D. Truesdale.
Columbus, USA, Ohio Supercomputer Center:
D. Johnson.
Copenhagen, Denmark, Niels Bohr Institute:
I. Bearden, H. Bøggild, C.H. Christensen, J.J. Gaardhøje, K. Gulbrandsen, B.S. Nielsen and G. Renault.
Cracow, Poland, Henryk Niewodniczanski Institute of Nuclear Physics, High Energy Physics
Department:
J. Bartke, E. Gładysz-Dziaduś, E. Kornaś, M. Kowalski, A. Rybicki and A. Wróblewski 17 .
Darmstadt, Germany, Gesellschaft für Schwerionenforschung (GSI):
S. Altinpinar, A. Andronic, D. Antonczyk, R. Bailhache, A. Bercuci E. Berdermann,
P. Braun-Munzinger, O. Busch, M. Ciobanu 18 , P. Foka, U. Frankenfeld, C. Garabatos, H. Gutbrod,
C. Lippmann, P. Malzacher, A. Marı́n, S. Masciocchi, D. Miśkowiec, S. Radomski, C.J. Schmidt,
H.R. Schmidt, K. Schwarz, R.S. Simon, D. Soyk, H. Stelzer, M. Stockmeier, G. Tziledakis and
D. Vranic, J. Wiechula.
Darmstadt, Germany, Institut für Kernphysik, Technische Universität:
U. Bonnes, I. Kraus and H. Oeschler.
Davis, USA, Department of Physics, University of California † :D. Ferenc and E. Lorenz.
Detroit, USA, Department of Physics, Wayne State University † :R. Bellwied, T.M. Cormier, M. Elnimr, A.I. Pavlinov, V.A. Petrov, C. Pruneau, J. Riso and
S.A. Voloshin.
East Lansing, USA, National Superconducting Cyclotron Laboratory, Michigan State University † :G.D. Westfall.
Frankfurt, Germany, Institut für Kernphysik, Johann Wolfgang Goethe Universität:
H. Appelshäuser, C. Blume, T. Dietel, M. Gaździcki, M. Hartig, M. Kliemant, S. Kniege, T. Kolleger,
F. Kramer, S. Lange, C. Loizides, M. Ploskon, R. Renfordt, W. Sommer, R. Stock and H. Ströbele.
Frascati, Italy, INFN Laboratori Nazionali di Frascati:
N. Bianchi, G.P. Capitani, G. Conesa Balbastre, E. De Sanctis, P. Di Nezza, A. Fantoni, C. Hadjidakis,
D. Hasch, V. Muccifora and F. Ronchetti.
Gatchina, Russia, St. Petersburg Nuclear Physics Institute:
Ya. Berdnikov, V. Ivanov, A. Khanzadeev, N. Miftakhov, V. Nikulin, V. Polyakov, E. Rostchin,
V. Samsonov, O. Tarasenkova, V. Tarakanov and M. Zhalov.
Grenoble, France, Laboratory for Subatomic Physics and Cosmology (LSPC)  :O. Bourrion, C. Furget, D. Grondin, S. Kox and J.-F. Muraz.
Havana, Cuba, Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN):
E. López Torres, A. Abrahantes Quintana and R. Dı́az Valdes.

iv
Heidelberg, Germany, Kirchhoff Institute for Physics:
T. Alt V. Angelov, J. Cuveland, S. Kalcher, U. Kebschull V. Lindenstruth, R. Panse, C. Reichling,
R. Schneider, T. Steinbeck, J. Thäder and G. Tröger
Heidelberg, Germany, Physikalisches Institut, Ruprecht-Karls Universität:Physikalisches Institut/ C. Adler, M. de Gaspari, D. Emschermann, P. Glässel, N. Herrmann,
W. Ludolphs, J. Mercado, J. Milosevic, R. Monroy-Gamboa, K. Oyama, I. Rusanov, R. Schicker,
K. Schweda, P. Shukla, H.K. Soltveit, R. Soualah, J. Stachel, G. Tsiledakis, B. Vulpescu,
B. Windelband and S. Yurevich.
Hiroshima, Japan, Hiroshima University  :K. Shigaki and T. Sugitate.
Houston, USA, Department of Physics, University of Houston † :A. Empl, B. Mayes and L. Pinsky.
Jaipur, India, Physics Department, University of Rajasthan:R. Raniwala and S. Raniwala.
Jammu, India, Physics Department, Jammu University:
S.K. Badyal, R. Bala, A. Bhasin, A. Gupta, V.K. Gupta, S. Mahajan, L.K. Mangotra,
B.V.K.S. Potukuchi and S.S. Sambyal.
JINR, Russia, Joint Institute for Nuclear Research:
P.G. Akichine, V.A. Arefiev, Ts. Baatar 19 , B.V. Batiounia, V.F. Chepurnov, S.A. Chernenko,
V.K. Dodokhov, O.V. Fateev, A.G. Fedunov, V.G. Kadychevsky, G. Kharadze 21 , B. Khurelbaatar19 ,E.K. Koshurnikov, V.L. Lioubochits, V.I. Lobanov, L.V. Malinina, Y.I. Minaev, M. Nioradze 22 ,P.V. Nomokonov, Y.A. Panebrattsev, V.N. Penev, V.G. Pismennaya, T.A. Pocheptsov, G.S. Shabratova,
A.I. Shklovskaya, M.K. Suleimanov, Y. Tevzadze 22 , R. Togoo19 , A.S. Vodopianov, V.I. Yurevich,
Y.V. Zanevsky, S.A. Zaporojets and A.I. Zinchenko
Jyväskylä, Finland, Department of Physics, University of Jyväskylä and Helsinki Institute of Physics:
J. Äysto, M. Bondila, V. Lyapin, M. Oinonen, T. Malkiewicz, V. Ruuskanen, H. Seppänen, W. Trzaska,
J. Rak and S. Yamaletdinov.
Kangnung, Republic of Korea, Kangnung National University:
H.T. Jung, W. Jung, D.-W. Kim, H.N. Kim, J.S. Kim, K.S. Lee and S.-C. Lee.
Karlsruhe, Germany, Institut für Prozessdatenverarbeitung und Elektronik (IPE)  :T. Blank and H. Gemmeke.
Kent, USA, Department of Physics, Kent State University † :D. Keane, S. Margetis and W. Zang.
Kharkov, Ukraine, National Scientific Centre, Kharkov Institute of Physics and Technology:
G.L. Bochek, A.N. Dovbnya, V.I. Kulibaba, N.I. Maslov, S.V. Naumov, V.D. Ovchinnik, S.M. Potin and
A.F. Starodubtsev.
Kharkov, Ukraine, Scientific and Technological Research Institute of Instrument Engineering:
V.N. Borshchov, O. Chykalov, S.K. Kiprich, L. Klymova, O.M. Listratenko, N. Mykhaylova,
M. Protsenko, O. Reznik and I.Tymchuk.

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Kiev, Ukraine, Department of High Energy Density Physics, Bogolyubov Institute for Theoretical
Physics, National Academy of Sciences of Ukraine:
O. Borysov, Y. Martynov, S. Molodtsov, S. Svistunov, S. Senyukov, Y. Sinyukov and G. Zinovjev
M. Zynovyev.
Knoxville, USA, Department of Physics, University of Tennessee † :Y. Kwon, K.F. Read and S. Sorensen.
Kolkata, India, Saha Institute of Nuclear Physics:
S. Bose, S. Chatterjee, S. Chattopadhyay, D. Das, I. Das, A.K. Dutt-Mazumder, S. Pal, L. Paul, P. Roy,A. Sanyal, S. Sarkar, S.K. Sen, B.C. Sinha and T. Sinha.
Kolkata, India, Variable Energy Cyclotron Centre:
Z. Ahammed, P. Bhaskar, S. Chattopadhyay, D. Das, M.R. Dutta Majumdar, M.S. Ganti, P. Ghosh,B. Mohanty, M.M. Mondal P.K. Netrakanti, S. Pal, S.K. Prasad, J. Saini, R.N. Singaraju, V. Singhal,
B. Sinha, and Y.P. Viyogi.
Köln, Germany, University of Applied Sciences Cologne, Communications Engineering  :G. Hartung and T. Krawutschke.
Košice, Slovakia, Institute of Experimental Physics, Slovak Academy of Sciences and Faculty of
Science, P.J. Šafárik University:
J. Bán, M. Bombara, A. Dirner, M. Hnatič, I. Králik, A. Kravčáková, F. Kriváň, M. Krivda,
G. Martinská, B. Pastirčák, L. Šándor, J. Urbán and J. Vrláková.
Legnaro, Italy, Laboratori Nazionali di Legnaro:
M. Cinausero, A. Dainese, E. Fioretto, G. Prete, R.A. Ricci and L. Vannucci.
Livermore, USA, Physics Division, Lawrence Livermore National Laboratory † :A. Enokizono, M. Heffner, J. Klay, J. Newby and R.A. Soltz.
Los Angeles, USA, Department of Physics, University of California † :V. Ghazikhanian, H.Z. Huang, S. Trentalange and C. Whitten, Jr.
Lund, Sweden, Division of Experimental High Energy Physics, University of Lund:
A. Oskarsson, L. Osterman, I. Otterlund and E.A. Stenlund.
Lyon, France, Institut de Physique Nucléaire de Lyon (IPNL), IN2P3-CNRS and Université Claude
Bernard Lyon-I:
B. Cheynis, L. Ducroux, J.Y. Grossiord, A. Guichard, P. Pillot, B. Rapp and R. Tieulent.
Mexico City and Mérida, Mexico, Centro de Investigación y de Estudios Avanzados del IPN,
Universidad Nacional Autónoma de México, Instituto de Ciencias Nucleares, Instituto de Fı́sica:
J.R. Alfaro Molina, A. Anzo, A. Ayala, E. Belmont Moreno, E. Castaneda, J.G. Contreras, E. Cuautle,
J.C. D’Olivo, I. Domı́nguez, L. Gonzalez, V. Grabski, G. Herrera Corral, H. Leon, M.I. Martı́nez,
A. Martı́nez Dávalos, A. Menchaca-Rocha, L.M. Montaño Zetina, L. Nellen, G. Paić 24 , C. Perez,
P. Podesta, A. Sandoval and A. Zepeda.
Moscow, Russia, Institute for Nuclear Research, Academy of Science:
V.A. Feshchenko, M.B. Golubeva, V.G. Gorlychev, F.F. Guber, O.V. Karavichev, T.L. Karavicheva,
E.V. Karpechev, A.B. Kurepin, A.I. Maevskaya, V.V. Marin, I.A. Pshenichnov, V.I. Razin,
A.I. Reshetin, K.A. Shileev and N.S. Topil’skaia.

vi
Moscow, Russia, Institute for Theoretical and Experimental Physics:
A.N. Akindinov, A.B. Kaidalov, S.M. Kiselev, E. Lyublev, D.B. Mal’kevich, M. Martemianov,
A.N. Martemiyanov, A.A. Nedosekin, A.V. Smirnitski, M.M. Tchoumakov, I.A. Vetlitski,
K.G. Voloshin and B.V. Zagreev.
Moscow, Russia, Russian Research Center Kurchatov Institute:
D. Aleksandrov, V. Antonenko, S. Beliaev, S. Fokine, M. Ippolitov, K. Karadjev, A. Kazantsev,
I. Koutcheriaev, V. Lebedev, V.I. Manko, T. Moukhanova, A. Nianine, S. Nikolaev, S. Nikouline,
O. Patarakine, D. Peressounko, I. Sibiriak, A. Vasiliev, A. Vinogradov and I. Yushmanov.
Moscow, Russia, Moscow Engineering Physics Institute:
V.A. Grigoriev, V.A. Kaplin and V.A. Loginov.
Mumbai, India, Indian Institute of Technology  :B.K. Nandi and R. Varma.
Mumbai, India, Bhabha Atomic Research Centre (BARC)  :V.B. Chandratre and S.K. Kataria.
Münster, Germany, Institut für Kernphysik Westfälische Wilhelms-Universität:
C. Baumann, R. Glasow, H. Gottschlag, N. Heine, C. Klein-Bösing, K. Reygers, R. Santo,
W. Verhoeven, J. Wessels and A. Wilk.
Nantes, France, Laboratoire de Physique Subatomique et des Technologies Associées (SUBATECH),
École des Mines de Nantes, IN2P3-CNRS and Université de Nantes:
L. Aphecetche, R. Berny, G. Bourdaud, S. Bouvier, Z. Conesa-del-Valle, J.P. Cussonneau,
H. Delagrange, M. Dialinas, Ch. Finck, B. Erazmus, S. Gadrat, M. Germain, F. Lefèvre, L. Luquin,
G. Martı́nez, Ch. Renard, C. Roy and A. Tournaire.
Novosibirsk, Russia, Budker Institute for Nuclear Physics:
A.R. Frolov and I.N. Pestov.
Oak Ridge, USA, Physics Division, Oak Ridge National Laboratory † :T.C. Awes, V. Cianciolo, Y.V. Efremenko, D. Silvermyr, P.W. Stankus and G.R. Young.
Omaha, USA, Creighton University:
M. Cherney, Y. Gorbunov and J. Seger.
Orsay, France, Institut de Physique Nucléaire (IPNO), IN2P3-CNRS and Université de Paris-Sud:
L. Bimbot, V. Chambert, A. Charpy, M.P. Comets, P. Courtat, S. Drouet, P. Edelbruck, B. Espagnon,
I. Hřivnáčová, Y. Le Bornec, J. Peyré, J. Pouthas, S. Rousseau, C. Suire and N. Willis.
Oslo, Norway, Department of Physics, University of Oslo:
L. Bravina, G. Løvhøiden, A. Nyiri, B. Skaali and T.S. Tveter.
Padua, Italy, Dipartimento di Fisica dell’Università and Sezione INFN:
F. Antinori, C. Bombonati, R. Dima, D. Fabris, J. Faivre, M. Lunardon, M. Morando, S. Moretto,
A. Pepato, E. Quercigh, F. Scarlassara, G. Segato, R. Turrisi and G. Viesti.
Pohang, Republic of Korea, Pohang University of Science and Technology, Department of Physics
and Pohang Accelerator Laboratory:
J. Choi.

vii
Prague, Czech Republic, Institute of Physics, Academy of Science:
A. Beitlerova, J. Mareš, K. Polák and P. Závada.
Prague, Czech Republic, Czech Technical University, Faculty of Nuclear Sciences and PhysicalEngineering:
V. Petráček, M. Pachr and L. Škoda.
Protvino, Russia, Institute for High Energy Physics:
M.Yu. Bogolyubsky, G.V. Khaustov, Yu.V. Kharlov, N.G. Minaev, V.A. Onuchin, V.S. Petrov,
B.V. Polichtchouk, S.A. Sadovsky, V.A. Senko, A.S. Soloviev, P.V. Stolpovsky and V.A. Victorov.
Puebla, Mexico, Benemérita Universidad Autónoma de Puebla:
A. Férnandez Téllez, E. Gamez Flores, I. León -Monzon, R. López-Ramı́rez, A. Ortiz-Velázquez,
C. Pagliarone25 , S. Román-López, G. Tejeda-Muñoz, A. Vargas, S. Vergara L. Villaseñor CendejasŘež u Prahy, Czech Republic, Academy of Sciences of Czech Republic, Nuclear Physics Institute:
D. Adamová, S. Kuchpil, V. Kuchpil, A. Kugler, M. Šumbera and V. Wagner.
Rome, Italy, Dipartimento di Fisica dell’Università ’La Sapienza’ and Sezione INFN:
S. Di Liberto, M.A. Mazzoni, F. Meddi and G.M. Urciuoli.
Saclay, France, Centre d’Études Nucléaires, DAPNIA:
A. Baldisseri, H. Borel, J. Castillo, J.-L. Charvet, J. Gosset, F. Orsini, H. Pereira and F.M. Staley
Salerno, Italy, Dipartimento di Fisica ‘E.R.Caianiello’ dell’Università and Sezione INFN:
A. De Caro, D. De Gruttola, S. De Pasquale, A. Di Bartolomeo, M. Fusco Girard, G. Grella,
C. Guarnaccia, M. Guida, S. Sellitto, R. Silvestri and T. Virgili.
Sarov, Russia, Russian Federal Nuclear Center (VNIIEF):
V. Basmanov, D. Budnikov, V. Demanov, V. Ianowski, R. Ilkaev, L. Ilkaeva, A. Khlebnikov,
A. Kouryakin, E. Mikhailov, S. Nazarenko, V. Pavlov, S. Philchagin, A. Punin, V. Punin, S. Poutevskoi,
A. Rybin, I. Selin, M. Smetanin, A. Telnov, S. Treskov, O. Vikhlyantsev, I. Vinogradov, A. Vyushin,
N. Zavyalov, S. Zhelezov and A. Zhitnik.
Seattle, USA, Department of Physics, University of Washington † :H. Bichsel, J.G. Cramer and D. Prindle.
Split, Croatia, Technical University of Split, Faculty of Electrical Engineering, MechanicalEngineering and Naval Architecture (FESB):
S. Gotovac, E. Mudnic and L. Vidak.
St. Petersburg, Russia, V. Fock Institute for Physics of St. Petersburg State University :A.G. Asryan, M.A. Braun, D.A. Derkach, G.A. Feofilov, S.N. Igolkin, A.S. Ivanov, R.S. Kolevatov,
A.A. Kolojvari, V.P. Kondratiev, P.A. Naumenko, T.A. Toulina, F.F. Valiev, V.V. Vechernin,
L.I. Vinogradov and A.K. Zarochentsev.
Seoul, Republic of Korea, Sejong University Department of Physics:
D.S. Hwang, C.Y. Choi, H.G. Kim and S. Kim
Strasbourg, France, Institut de Recherches Subatomiques (IReS), IN2P3-CNRS and Université Louis
Pasteur:J. Baudot, D. Bonnet, J.P. Coffin, M. Estienne, B. Hippolyte, C. Kuhn, J.R. Lutz, S. Plumeri and
R. Vernet.

viiiTokyo, Japan, University of Tokyo,  :H. Hamagaki and K. Ozawa.
Trieste, Italy, Dipartimento di Fisica dell’Università and Sezione INFN:
V. Bonvicini, O. Borysov26 , L. Bosisio, M. Bregant, P. Camerini, E. Cattaruzza, G. Contin,
E. Fragiacomo, N. Grion, G. Margagliotti, S. Piano, I. Rachevskaya, A. Rachevski, R. Rui and
F. Soramel29 , A. Vacchi.
Turin, Italy, Dipartimenti di Fisica dell’Università and Sezione INFN:
B. Alessandro, R. Arnaldi, S. Bagnasco, G. Batigne, S. Beolé, E. Bruna, P. Cerello, E. Chiavassa,
O. Cobanoglu, S. Coli, E. Crescio, N. De Marco, P. De Remigis, A. Ferretti, M. Gagliardi, M. Gallio,
L. Gaudichet, R. Gemme, G. Giraudo, P. Giubellino, M. Idzik, S. Martoiu, A. Marzari Chiesa,
M. Masera, G. Mazza, P. Mereu, M. Monteno, A. Musso, C. Oppedisano, A. Piccotti, F. Poggio,
F. Prino, L. Riccati, A. Rivetti, E. Scomparin, S. Senyukov, L. Simonetti, D. Stocco, F. Tosello,
L. Toscano, E. Vercellin, R. Wheadon and F. Yermia.
Tsukuba, Japan, University of Tsukuba,  :Y. Miake and S. Esumi.
Utrecht, The Netherlands, Subatomic Physics Department, Utrecht University and National Institutefor Nuclear and High Energy Physics (NIKHEF):
A.P. De Haas, C. Ivan, R. Kamermans, A. Mischke, G. Nooren, C.J. Oskamp, Th. Peitzmann, E. Simili,
O. Sokolov, A. Van Den Brink and N. Van Eijndhoven.
Wako-shi, Japan, RIKEN  :H. Enyo, K. Fujiwara, H. Kano and H. Onishi.
Warsaw, Poland, Soltan Institute for Nuclear Studies:
A. Deloff, T. Dobrowolski, K. Karpio, M. Malek, H. Malinowski, K. Redlich 27 , T. Siemiarczuk,
G. Stefanek28 , L. Tykarski and G. Wilk.
Warsaw, Poland, University of Technology, Institute of Physics:
Z. Chajecki, H. Gos, M. Janik, M. Jedynak, A. Kisiel, T.J. Pawlak, W.S. Peryt, J. Pluta, P. Skowronski,
M. Slodkowski, P. Szuba and T. Traczyk.
West Lafayette, USA, Department of Physics, Purdue University † :R.P. Scharenberg, B. Srivastava and F.H. Wang.
Worms, Germany, University of Applied Sciences Worms, ZTT  :E.S. Conner and R. Keidel.
Wuhan, China, Institute of Particle Physics, Huazhong Normal University:
X. Cai, H.T. Ding, H. Liu, X.R. Wang, H.Y. Yang, Z.B. Yin and D.C. Zhou.
Wuhan, China, Huazhong Univ. of Science and Techn. Electronic and Inform. Engineering:
X. Cao, Q.X. Li, Y.Z. Liu, G. Su, L. Tan, and G.X. Zhu.
Yerevan, Armenia, Yerevan Physics Institute:
M. Atayan, A. Grigoryan, H. Gulkanyan, A. Harutyunyan, A. Hayrapetyan, V. Kakoyan, M. Poghosyan,
T. Poghosyan and G. Sargsyan.

ix
Zagreb, Croatia, Ruder Bošković Institute:
T. Anticić, K. Kadija and T. Susa.

 Associate member.
Applying to join the collaboration.
1 Marie Curie fellow at Physics Department, CERN, Geneva, Switzerland.
2 On leave from Institute of Particle Physics, Huazhong Normal University, Wuhan, China.
3 On leave from Institute of Experimental Physics, Košice, Slovakia.
4 Now at Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany.
5 On leave from JINR, Dubna, Russia.
6 Supported by EGEE.
7 On leave from INFN CNAF, Bologna, Italy.
8 National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
9 On leave from Division of Experimental High Energy Physics, University of Lund, Lund, Sweden.
10 On leave from Comenius University, Faculty of Mathematics, Physics and Informatics, Bratislava,
Slovakia.
11 Now at INFN, Sezione di Firenze, Firenze, Italy.
12 On leave from Variable Energy Cyclotron Centre (VECC), Kolkata, India.
13 On leave from INFN, Sezione di Torino, Turin, Italy.
14 On leave from Laboratoire de Physique Subatomique et des Technologies Associées (SUBATECH),
Ecole des Mines de Nantes, IN2P3-CNRS and Université de Nantes, Nantes, France.
15 On leave from Budapest University, Budapest, Hungary.
16 On leave from Yerevan Physics Institute, Yerevan, Armenia.
17 Cracow Technical University, Cracow, Poland.
18 On leave from National Institute for Physics and Nuclear Engineering, Bucharest, Romania.
19 Institute of Physics and Technology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia.
20 Institute of Space Sciences, Bucharest, Romania.
21 Institute of Physics, Georgian Academy of Sciences, Tbilisi, Georgia.
22 High Energy Physics Institute, Tbilisi State University, Tbilisi, Georgia.
23 Research Centre for Applied Nuclear Physics (RCANP), Dubna, Russia.
24 Department of Physics, Ohio State University, Columbus, USA.
25 On leave from Universitá degli Studi di Cassino and INFN, Pisa, Italy.
26 On leave from Department of High Density Physics, Kiev, Ukraine.
27 Institute of Theoretical Physics, University of Wroclaw, Wroclaw, Poland and Physics Department,
CERN, Geneva, Switzerland.
28 Institute of Physics, Pedagogical University, Kielce, Poland.
29 Udine, Italy, Dipartimento di Fisica dell’Universita’ and Gruppo Collegato INFN
30 On leave from Bari, Italy, Dipartimento di Fisica dell’Università and Sezione INFN.
31 Presently at Kent, USA, Kent State University.
32 On leave from Münster, Germany, Institut für Kernphysik Westfälische Wilhelms-Universität.
†xAcknowledgements
The Collaboration wishes to thank all the administrative and technical staff involved during the preparation of the EMCal Addendum to the ALICE TP and in particular: the ALICE secretariat, M. Connor, U.
Genoud, and C. Hervet; the CERN Desktop Publishing Service, in particular S. Leech O’Neale and C.
Vanoli; and the CERN printshop.

xii

xiii

Contents2

Detector Design
2.1
Design Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2Module Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2.1
Sampling Fraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2.2
Optical System and Photo Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3
Module Integration to Strip Modules and Super Modules . . . . . . . . . . . . . . . . . .
2.4
Mechanical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4.1
Super Module Crate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.4.2
Strip Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2
2
3
4
6
9
11
12
12

References

13

xiv

2

2 Detector Design

2.1 Design Overview
The overall design of the EMCal is heavily influenced by its integration within the ALICE [1] magnet.
The EMCal is to be located inside the large room temperature solenoidal magnet of ALICE within acylindrical integration volume approximately 112 cm deep in the radial direction sandwiched between
the ALICE spaceframe and the ALICE magnet coils. Due to the installation of the PHOS carriage below
the ALICE TPC and the HMPID above the ALICE TPC, the EMCal is limited to a region of about
110 degrees in azimuth above the TPC adjacent to the HMPID. As discussed in Section ??,this EMCal
acceptance is well matched to ALICE physics goals.
The conceptual design of the electromagnetic calorimeter for the ALICE experiment is based on
the Shashlik technology as implemented in the PHENIX experiment [2] at RHIC, HERA-B at DESY
or LHCb [3] at CERN. The scope and basic design parameters of the proposed calorimeter have beenchosen to match the physics performance requirements of the high p t physics program.

Figure 2.1: The array of super modules shown in the installed position on their support structure.
Fig. 2.1 shows the EMCal super modules mounted in the installed position on their support structure.
A continuous arch of super modules, each spanning  20 degrees in azimuth, is indicated. The EMCal
is positioned to provide partial back-to-back coverage with the ALICE Photon Spectrometer (PHOS)

2.2

Module Design

3calorimeter. Small azimuthal gaps (  3  0 cm) are provided between super modules to facilitate installation and alignment. These gaps are positioned in line with the TPC sector boundaries. Along these
sector boundaries, there is substantial additional structural material required for the support of the TPC
and other ALICE detectors that would significantly degrade any electromagnetic measurements made inthese gaps.
The chosen technology is a layered Pb-scintillator sampling calorimeter with a longitudinal pitchof 1.44 mm Pb and 1.76 mm scintillator 1 with longitudinal wavelength shifting fibre light collection(Shashlik). The full detector spans η = -0.7 to η = 0.7 with an azimuthal acceptance of ∆φ = 110  . The
detector is segmented into 12672 towers, each of which is approximately projective in η and φ to theinteraction vertex.
The towers are grouped into super modules of two types: full size which span ∆η =0.7 and ∆φ = 20  ,and half size which span ∆η = 0.7 and ∆φ = 10  . There are 10 full size and 2 half size super modules in
the full detector acceptance (Fig. 2.1). The super module is the basic structural units of the calorimeter.
These are the units handled as the detector is moved below ground and rigged during installation. Fig. 2.2
shows a super module with its external mechanical structure stripped away to illustrate the stacking ofmodules within the super module.

Figure 2.2: ALICE EMCal super module concept.
This figure shows a full size super module with 12  24 modules configured as 24 strip modulesof 12 modules each. The supporting mechanical structure of the super module has been removed sothat the strip module stacking into a nearly projective geometry can be seen. The electronics integration
pathways are illustrated.
Each full size super module is assembled from 12  24  288 modules arranged in 24 strip modulesof 12  1 modules each. Each module has a rectangular cross section in the φ direction and a trapezoidal
cross section in the η direction with a full taper of 1.5  . The resultant assembly of stacked strip modules
is approximately projective with an average angle of incidence of less than 2  in η and less than 5  in φ.
A single module and an assembled strip module is indicated schematically in Fig. 2.3

2.2 Module Design
The smallest building block of the calorimeter is the individual module illustrated in Fig. 2.3. Eachindividual module contains 2  2  4 towers built up from 77 alternating layers of 1.44 mm Pb (1%1 To best account for materials in the space immediately before the calorimeter, the first layer of the detector is scintillator.

42

Detector Design

Figure 2.3: A single 1  5  taper module (right hand side) with the dimensions of the prototype shown in mm. The
left hand figure shows a single strip module comprised of 12 EMCal modules integrated onto a single strong back.

Antimony Pb) and 1.76 mm polystyrene, injection moulded scintillator. White, acid free, bond paper
serves as a diffuse reflector on the scintillator surfaces while the scintillator edges are treated with TiO 2
loaded reflector to provide tower to tower optical isolation and improve the transverse optical uniformity
within a single tower.
The Pb-scintillator stack in a module is secured in place by the static friction between individual
layers under the load of an internal pressure of  1.3 kg/cm 2 . The module is closed by a skin of 100 µm
thick stainless steel welded on all four transverse surfaces to corresponding front and rear stainless steel
plates. This thin stainless skin is the only inert material between the active tower volumes. The internalpressure in the module is stabilized against thermal effects, mechanical relaxation and long term flow of
the Pb and/or polystyrene by a customized array of 5 non-linear spring 2 sets per module. In this way,each module is a self supporting unit with a stable mechanical lifetime of more than 20 years when heldfrom its back surface in any orientation as when mounted in a strip module. Fig. 2.4 shows a cut away
view of the back end of a single module illustrating the internal components used to sustain the module
compression and a segment of the strip module strong back.
All modules in the calorimeter are mechanically and dimensionally identical. The front face dimensions of the towers are  6  6 cm2 resulting in individual tower acceptance of ∆η  ∆φ  0  014  0  014
at η=0.

2.2.1 Sampling Fraction
The present conceptual design incorporates a moderate detector average active volume density of  5.68
g cm3 which results from a  1 : 1  22 Pb to scintillator ratio by volume. This results in a compact detector consistent with the EMCal integration volume at the chosen detector thickness of  20  1 radiation
2 Bellville Washers, Rolex Inc.

2.2

Module Design

5

Figure 2.4: Cut away view of the back end of a single module showing the components that maintain the module’s
compression. A segment of the strip module strong back is also shown.

lengths (  20  1 X0 ). In simulations, this number of radiation lengths gives a maximum deviation fromlinearity (due mainly to shower leakage) of  5% for the mean energy response in the range up to 100
GeV photons which is deemed acceptable.
The energy resolution of an electromagnetic calorimeter can be parameterized as

σ E a

E

b

c E

(2.1)

where the first term characterized by the parameter a arises from stochastic fluctuations due to intrinsic
detector effects such as energy deposit, energy sampling, light collection, etc. The constant term, b,
arises from systematic effects, such as shower leakage, detector non-uniformity or channel-by-channel
calibration errors. The third term, c, arises from electronic noise summed over the towers of the cluster used to reconstruct the electromagnetic shower. The three resolution contributions add together inquadrature as indicated in Eq. 2.1. Over the lower half of the energy range of interest in ALICE, thestochastic term dominates with the constant term increasing in significance at the highest energies.
The energy resolution for a given sampling frequency in a sampling electromagnetic calorimeter
varies with the sampling frequency approximately as σ E  dSc fs where dSc is the scintillator thickness in mm and f s is the sampling fraction for minimum ionizing particles. For optimum resolution
in a given physical space and total radiation lengths, there is thus a desire to have the highest possible
sampling frequency. Practical considerations, including the total assembly labour, suggest reducing thetotal number of Pb/scintillator layers thus decreasing the sampling frequency. Using the 1:1.22 Pb toscintillator ratio described above as a compromise - a sampling geometry of Pb(1.44 mm)/Scint(1.76mm) - detailed GEANT3 simulations yield a E b% with the fit results a  6  90  0  09  % andb  1  44  0  03  % over the range pt  5 to 100 GeV c. The simulation results are shown in Fig. 2.5.
These results are based on energy deposition only and at the moment do not include photon transport62

Detector Design

DE vs Eγ : : 77 layers, 1.44mm(Pb)x1.76mm(Sc)DE vs Eγ : : 77 layers, 1.60mm(Pb)x1.60mm(Sc)44

χ2 / ndf

3.5
3

2.5

8.596 / 5A

1.443 ± 0.026

B

6.895 ± 0.088

Resolution %Resolution %efficiencies or the electronic noise contribution. Some increase in the constant a is expected from photontransport and related effects. This has been studied in test beam measurements of an early prototype of
this detector with a lower sampling frequency - Pb(1.6 mm)/Scint(1.6 mm) also shown in Fig. 2.5 - andpreliminary results are consistent with a small increase in a as shown in Section ??. This will receive
further study in forthcoming test beams with precisely the detector geometry described in this proposal.
The value of the constant term b is dominated by shower leakage in these calculations. Other systematiceffects which arise during detector fabrication and from the tower-by-tower calibration uncertainties will
increase b. The latter effect is itself of the order of 1% typically. The ongoing program of test beammeasurements is described in Section ??.

A

1.047 ± 0.015

2.5

B

7.906 ± 0.051

2

1.5

1.5
2

A2+B
E

0.5
0

20

40

2

A2+B
E

1
0.5
60

80

100
Eγ GeV/c

10.55 / 5

32

1

χ2 / ndf

3.5

0

20

40

60

80

100
Eγ GeV/c

Figure 2.5: GEANT3 simulations of the EMCal module resolution. Left: Proposed production module. Right:
Prototype test module.

The impact of detector energy resolution on the proposed physics program has been studied. While,
given the nature of the proposed physics, there is no sharp cutoff, an energy resolution for isolated
electromagnetic clusters on the order of  12% E 2% is found to be sufficient. Based on simulations
and test beam results, it is expected that the EMCal performance requirements are readily met in therelevant pt range by the proposed sampling choice. This is discussed further in connection with first test
beam results in Section ??.
The physical characteristics of the EMCal are summarized in Table 2.1.

2.2.2 Optical System and Photo Sensors
Scintillation photons produced in each tower are captured by an array of 36 Kuraray Y-11, double clad,
wavelength shifting (WLS) fibres that run longitudinally through the Pb/scintillator stack. Each fibre
terminates in an aluminized mirror at the front face end of the module and is integrated into a polished,circular group of 36 at the photo sensor end at the back of the module. Because the tower transverse
shape deviates slightly from square as a function of longitudinal depth, we choose a fibre pattern which
has exactly the same aspect ratio as the mechanical tower shape at a depth close to shower maximum.
This has the effect of making the fibre pattern uniform across tower boundaries when weighted by theshower energy deposition. The properties of the selected fibres are given in Table 2.2.
The fibre bundles are pre-fabricated and inserted into the towers after the module mechanical assembly is completed. A prototype fibre bundle is shown in Fig. 2.6. The 36 individual fibres are packed
into a circular array 6.8 mm in diameter and held in place inside a custom injection moulded grommet
by Bicron BC-600 optical cement. An optical quality finish is applied to the assembled bundle using

2.2

Module Design

7

Quantity

Table 2.1: The EMCal Physical Parameters.
Value

Tower Size (at η=0)
Tower Size
Sampling Ratio
Number of Layers
Effective Radiation Length Xo
Effective Moliere Radius RM
Effective Density
Sampling Fraction
Number of Radiation Lengths
Number of Towers
Number of Modules
Number of Super Modules
Weight of Super Module
Total Coverage

 6.0  6.0  24.6 cm3 (active)∆φ x ∆η = 0.0143 x 0.0143
1.44 mm Pb / 1.76 mm Scintillator
77
12.3 mm
3.20 cm
5.68 g/cm3
10.5
20.1
12,6723168
10 full size, 2 half size
 7.7 metric tons (full size)∆φ = 110o , -0.7  η  0.7

a diamond polishing machine. At the other end of the bundle, individual fibres are similarly polishedand mirrored with a sputtered coat of aluminum and a sputtered overcoat of Al 2 O3 for protection of themirror.

Figure 2.6: A prototype EMCal fibre bundle of 36 fibres.
A number of optical studies have been completed to assess the light transmission through individual
fibres and the efficacy of the mirror applied to the fibre end at the front face of the calorimeter. In thesetests, a single optical fibre connected to a UV LED light source was used to inject light of fixed amplitude
at varying positions along the fibre. Tests were made with and without mirroring applied to the polishedfibre end and transmitted light was recorded with an Avalanche Photo Diode (APD) photosensor as afunction of position of the light injection point. Typical results are shown in Fig. 2.7. In this figure, theAPD sits at zero distance and the front face of the calorimeter, in a full detector assembly, would sit at the82

Detector Design

distance of approximately 33 cm. The lower curve shows the light transmission efficiency in arbitrary
units as a function of distance from the APD for a fibre without mirrored end. The upper curve showsthe effect of including mirroring on the fibre end. The response is considerably flatter with an overall
increase in efficiency in the range of about 25% in the vicinity of shower maximum (i.e. the location of
the highest energy deposition for an electromagnetic shower). Shower maximum occurs at about 26 cm
on the distance scale of Fig. 2.7. This number accounts for material immediately in front of the detector;
which ranges between 0.4 and 0.8 radiation lengths, and assumes 5.5 - 6.0 radiation lengths for shower
maximum for 10 GeV photons. At this depth in the detector, the mirrored fibre response is very uniform
and contributes nothing significant to the non-linearity of the detector as a whole.

Figure 2.7: Comparison of light transmission efficiency versus distance of propagation for Kuraray Y-11 fibres
with and without aluminized mirrored ends.
Other factors which can significantly impact the electromagnetic performance of the calorimeter, include scintillator edge treatment and the density of the wavelength shifting fibre readout pattern and thematerial chosen for the interlayer diffuse reflector. For scintillator edge treatment and fibre density, wewere able to take advantage of the extensive studies made by the LHCb collaboration for their ECAL [3].
Given that we use the same scintillator with virtually identical towers size to the LHCb ”middle modules”, we were able to adopt their procedures for scintillator edge treatment and fibre density after aseries of relatively simply checks. In particular, we have adopted a diffuse reflector edge treatment suchas that obtained with Bicron Titanium Dioxide loaded white paint (BC622A) and a total fibre density of
about one fibre per cm2 . In the case of the interlayer diffuse reflector, we have to deviate from LHCb
and use a white, acid free, bond paper in place of the Teflon based commercial TYVEK. While TYVEK
produces slightly better surface reflectivity, its coefficient of friction is too low to permit its use in thisdesign where the module’s mechanical stability depends somewhat on the interlayer friction. The white2.3

Module Integration to Strip Modules and Super Modules

9

paper used in the EMCal prototypes has been previously studied for aging effects in connection with theSTAR calorimeter project [4].
Table 2.2: Characteristics of the selected wavelength shifting fibres.
QuantityValue
WLS Fibre
Manufacturer
WLS Fluor
Absorbtion PeakEmission Peak
Decay Time
Core material
Refractive Index
Inner Cladding
Refractive Index
Outer Cladding
Refractive Index
Long Fibre Attenuation Length
Fibre DiameterY-11 (200) M-DC
Kuraray
K27 200 mg
430 nm476 nm
7 ns
PS
1.59
PMMA
1.49
FP
1.42
3.5 m
1.0 mmThe 6.8 mm diameter fibre bundle from a given tower connects to the APD through a short lightguide/diffuser with a square cross section of 7 mm  7 mm that tapers slowly down to 4  5 mm  4  5 mm
as it mates (glued) to the 5 mm  5 mm active area of the photo sensor.
Fig. 2.8 shows 4 pre-fabricated fibre bundles inserted into the towers of a single prototype module.
In this picture all of the module rear enclosing and structural elements are omitted so the convergence of
the wavelength shifting fibres may be seen as they converge to the light guide (inside the black plastictube) and finally to mate with the APD and charge sensitive preamplifier. The APD and preamplifier
are discussed at length in Section ??. Here we will mention briefly their optical characteristics. The
selected photo sensor is the Hamamatsu S8664-55 Avalanche Photo Diode. This photodiode has a peak
spectral response at a wavelength of 585 nm compared to an emission peak of 476 nm for the Y-11
fibres. However, both the spectral response and the quantum efficiency of the APD are quite broad withthe latter dropping from the maximum by only  5% at the WLS fibre emission peak. At this wavelength,
the manufacturer’s specification gives a quantum efficiency of 80%.

2.3 Module Integration to Strip Modules and Super Modules
As described above, the super module is the basic building block of the calorimeter. Starting with 288
individual modules which are rather compact and heavy, the main engineering task is to create a supermodule structure which is rigid, with small deflections in any orientation yet does not require extensive,
heavy external stiffening components that would reduce the volume available for the active detector. The
solution adopted for the ALICE EMCal is to develop a super module ”crate” which functions not as a box
for the individual modules but rather an integrated structure in which the individual elements contributeto the overall stiffness. The super module crate is effectively a large I-beam in which the flanges are thelong sides of the crate and the 24 rows of strip modules together form the web. This configuration gives
to the super module good stiffness for both the 9 o’clock and 10 o’clock locations. For the 12 o’clock
location, the I-beam structure of the super module is augmented by a 1 mm thick stainless steel forward
sheet (traction loaded), which controls the bending moment tending to ”open” the crate main sides, andhelps to limit deflection of strip modules.

102

Detector Design

Figure 2.8: Fibre bundles with attached APD and preamplifier of four towers of an EMCal module.

The super module crate concept is illustrated in Figs. 2.9 and 2.10. For the purpose of clarity in these
illustrations, only 6 of the 24 strip modules are included. Ridges are provided on the interior surfaces of
the crate to allow precision alignment of the strip modules at the correct angle.
The stiffness given by this I-beam concept allows the use of non-magnetic light alloys for main partsof the super module crate. Unlike austenitic stainless steels, light alloys are easy to machine, helping tolimit both cost and weight. Parts of the super module crate will be made mainly from laminated 2024
aluminum alloy plates. The two main sides (flanges of the I-beam) of the crate will be assembled from 2
plates, 25 mm and 25 mm thick, bolted together and arranged so as to approximately follow the taper ofthe 20 degree sector boundary.
Each of the 24 rows of a super module contain 12 modules as described in Section 2.4. Each of themodules is attached to a transverse beam by 3–4 mm diameter stainless steel screws. The 12 modules
and the transverse beam form a strip module.
The strip module is roughly 1440 mm long, 120 mm wide, 410 mm thick. The total weight of the
strip module is approximately 300 kg and like module, it is a self supporting unit. The transverse beam,
which is the structural part of the strip module, is made from cast aluminum alloy with individual cavities
along its length where the fibres emerging from towers are allowed to converge. The casting process iswell suited to forming these cavities and the overall structure, saving considerable raw material andmachining time. Fig. 2.11 shows the overall layout and dimensions of a strip module.
In addition to functioning as a convenient structural unit which offers no interference with the active
volume of the detector and forming the web of the I-beam structure of the super module, the transverse
beam of the strip module provides protection for the fibres, a structural mount for the light guide, APD
and charge sensitive preamplifier and a light tight enclosure for these elements.

2.4

Mechanical Analysis

11

Figure 2.9: Conceptual layout of the super module crate. Only six of the 24 strip modules are inserted in thisfigure for clarity - two near the zero rapidity end, two near the center and two near the high rapidity end.

Figure 2.10: A side view of the super module crate showing the function of the ridges used to align the strip
modules. Only six strip modules are shown here for clarity.

Figure 2.11: Strip module layout showing dimensions and the 1.5 degree taper.

2.4 Mechanical Analysis
Analysis of the strip modules and super modules was performed with the CATIA application for 3Dmodeling and Samcef Field for Finite Element analysis (FEA). All calculations were performed for a122

Detector Design

super module mass of approximately 9950 kg. This super module mass results in a total weight for the
EMCal detector of 110 tons and corresponds to a detector with an active depth of 22 radiation lengths.
This total weight is close to the upper limit still providing a sufficient safety factor for support surfaces in
the ALICE magnet. The detector considered in this proposal actually has an active depth of 20 radiation
lengths and has approximately 10% less mass than the detector modeled in the analysis. This 10% may
be viewed as an extra safety factor or may be regarded as a margin to permit some increase in the active
detector depth should future simulations of physics performance suggest that this is required.

2.4.1 Super Module Crate
FEA calculations show, for a load of 100 kN, a maximum stress of roughly 20 Mpa at 12 o’clock locationand 120 Mpa at 9 o’clock location. These points of maximum stresses occur close to the super module
mounting points at the carriages (Figs. 2.9 and 2.10). This level of stress is acceptable for the 2024
aluminum alloy which performs to a 290 Mpa yield strength. The crate features a deformation of 0.8–
1.0 mm at the 9 o’clock location.

2.4.2 Strip Module
Calculations show that the cast strip module will have a maximum stress less than 15 Mpa while 42000
cast aluminum alloy performs to a yield strength of 180 Mpa. The maximum deflection of a strip module
is foreseen at 0.7–0.9 mm, for the 12 o’clock location.

13

References
Chapter 2[1] ALICE Collaboration, A Large Ion Collider Experiment, CERN/LHCC 95-71, 15 December 1995.
[2] L. Aphecetche et. al., (PHENIX), Nucl. Instrum. Methods A499 (2003) 521.
[3] LHCB Collaboration, LHCb TDR2, CERN/LHCC 2000-36, 6 September 2000.
[4] M. Beddo et al, The STAR barrel electromagnetic calorimeter, Nucl. Instrum. Methods A499
(2003) 725.

14

Federico Ronche, / Manoel Dialinas

2008.7.10

MODULE COMPONENTS
Front Plate
Back Plate
Compression Plate
StrapsLead Absorber
ScinNllator Tile
Bond Paper
Fiber Bundle Terminator
Strap Flange
Belleville Washers Plunger Pin
Dowel Pin (CP ‐ BP)Black SNcker
Stud (ﬁxaNon module‐strongback)Bushing
Strap Foil
Plunger Pin Pusher
Belleville Washers

26K2xx26K20026K201
26K202
26K203
26K204
26K205
26K206
26K207
26K208
26K20926K21026K211
26K212
26K213
26K214
26K215STRIP MODULE COMPONENTS

26K3xxStrongBack casNng
StrongBack machining
LED Ferrule
T‐CardT‐Card FixaNon
Central Cover Plate
Preampl Fiber Manifold
Light Guide
APD mount
TCardStud
Bridge CoverSide Cover Plate

26K301
26K302
26K303
26K304
26K305
26K306
26K307
26K308
26K30926K31026K311
26K312SUPER MODULE COMPONENTS
Montage Crate
Nomenclature
Nomenclature
Face inférieure gauche
Face inférieure droite
Face supérieure gauche
Face supérieure droite
Pièces arrière
Plaque inférieure
Pièce inférieure
Face appui arrière

26K4xx26K40026K401
26K402
26K403
26K404
26K405
26K406
26K407
26K408
26K40926K410STRIPMODULE TOOLINGS
Base_Granit
SupportRod
Rib
Lid Table
Set Up Device 1
Set Up Device 2
LocaNng Pin
Support

26K5xx26K501
26K502
26K503
26K504
26K505
26K506
26K507
26K508
26K509SUPERMODULE TOLINGS

26K6xxLast Rev.
J released
I released
F released
E released
C released
A approved
B approved
D released
H released
C released
A removed

Rev. Time2008.4.7
2008.4.7
2008.4.8
2008.4.4
2008.4.9
2007.6.12
2008.3.5
2008.4.25
2008.4.8

Order Time2008.4.1
2008.4.1
2008.4.1

Company
Mecanotecnica
Mecanotecnica
Mecanotecnica
LRA
Goslar
Uniplast
FFT

2008.4.10

GardeUe
Mecanotecnica

Delivered
Delivered
DeliveredSony
A released
A removed
B approved
D released

2008.1.10
2008.4.11

2008.4.8

LPSC
Schnorr

C approved
D released
A approved
A approved
B released
A released
B released
A released
C released
A released

2008.3.4
2008.3.19
2007.12.12

A released

2008.3.17

E released

2008.3.27

B3

G released
G released
F released
F released
E released
D released
E released
E released

2008.4.1
2008.4.1
2008.3.27
2008.3.27
2008.3.27
2008.3.27
2008.3.27
2008.3.27

B3
B3
B3
B3
B3
B3
B3
B3

A released
A released

2008.4.7
2008.4.7

MicroPlan
Meca AtlanNque

2008.2.18
2008.3.17
2008.2.19
2007.12.7
2008.3.5
2008.1.15

2008.3.10
2008.3.10

Renouard
Mecaria

Uniplast

delivereddelivered