NUCLEAR INSTRUMENTS Nuclear Instruments and Methods in Physics Research A 336 (1993) 499-509 & METHODS North-Holland IN PHYSICS RESEARCH Section A Results from pion calibration runs for the H 1 liquid argon calorimeter and comparisons with simulations H 1 Calorimeter Group B. Andrieu °, J . Bân', E. Birrelet °, H. Bergstein a, G. Bernardi °, M. Besançon', E. Binder h, H. Blume m, f, K. Borras V. Boudry °, F. Brasse h, W. Braunschweig a, V. Brisson n, A.J. Campbell s, T. Carli °, M. Colombo f, Ch. Coutures', G. Cozzika `, M. David', B. Delcourt °, L. DelBuono P, M. Devel n, P. Dingus °, A. Drescher f, J. Duboc P, O. Diinger', R. Ebbinghaus f, S. Egli ", N.N . Ellis c, J . Feltesse `, t, h, m, h, Y. Feng P, F. Ferrarotto s, W. Flauger M. Flieser m, K. Gamerdinger J. Gayler L. Godfrey e, m, L. Goerlich d, M. Goldberg P, R. Grdssler b, T. Greenshaw', H. Greif M. Haguenauer °, L. Hijduk d, O. Himon P, P. Hartz f, V. Haustein', R. Hiydar n, W. Hildesheim P, N. Huot P, M .-A . Jabiol 1, n, n, m, e, A. Jacholkowska M. Jaffre H. Jung b, F. Just °, C. Kiesling Th . Kirchhoff h, F. Kole d,t, m, e, V. Korbel h, M. Korn f, W. Krasny J.P. Kubenka H. Kiister h, J. Kurzhbfer f, B. Kuznik n, R. Lander t, m, J .-F . Laporte `, U. Lenhirdt f, P. Loch h, D. Lüers J. Marks s, J. Martyniak d , T. Merz h, B. Niroska', A. Nau h , H.K. Nguyen P, F. Niebergall', H. Oberlack', U. Obrock f, F. Ould-Saada', n, m, C. Pascaud H.B. Pyo h, K. Rauschnabel f, P. Ribarics M. Rietz b, Ch. Royon `, V. Rusinov t, b, m, a, h, N. Sahlmann E. Sânchez P. Schacht m, P. Schleper W. von Schlippe k, C. Schmidt D. Schmidt', t,f, V. Shekelyan H. Shooshtari s, Y. Sirois °, P. Stiroba q, M. Steenbock', H. Steiner P, B. Stella', a, m, U. Straumann ", J. Turnau d, J. Tutas L. Urban C. Vallee P, M. Vecko v,°, P. Verrecchia `, G. Villet t, n,r, E. Vogel a, A. Wagener b, D. Wegener f, A. Wegner', H.-P . Wellisch m, T.P. Yiou P, J. 2âcek Ch. Zeitnitz h and F. Zoiner n a I. Physikalisches Institut der RWTH, Aachen, Germany b III. Physikalisches Institut der RWTH, Aachen, Germany School of Physics and Space Research, University of Birmingham, Birmingham, UK ** d Institutefor Nuclear Physics, Cracow, Poland e Physics Department and IIRPA, University of California, Divas, CA, USA $ f Institut für Physik, Universität Dortmund, Dortmund, Germany s Department of Physics and Astronomy, University of Glasgow, Glasgow, UK ** h DESY, Hamburg, Germany ' II Institut für Experimentalphysik, Universität Hamburg, Hamburg, Germany J Institute of Experimental Physics, Slovak Academy of Sciences, Kosice, Slovakia k Queen Mary and Westfield College, London, UK ** e Institute for Theoretical and Experimental Physics, Moscow, Russian Federation m Max-Planck-Institut für Physik, München, Germany n LAL, Université Paris-Sud, IN2P3-CNRS, Orsay, France ° LPNHE, Ecole Polytechmque,IN2P3-CNRS, Palaiseau, France P LPNHE, Universit& Paris VI and VII, IN2P3-CNRS, Paris, France q Institute of Physics, Czech Academy of Sciences, Praha, Czech Republic Nuclear Center, Charles University, Praha, Czech Republic s INFN Roma and Dipartimento di Fisica, Universita "La Sapienzia", Roma, Italy t DAPNIA, Centre d Etudes de Saclay, Gif-sur- Yvette, France * Fachbereich Physik, Bergische Universität Gesamthochschule Wuppertal, Wuppertal, Germany Physik-Institut der Universität Zürich, Ziirich, Switzerland $$ Received 15 April 1993 and in revised form 30 June 1993 We present results on calibration runs performed with pions at the CERN SPS for different modules of the H 1 liquid argon calorimeter which consists of an electromagnetic section with lead absorbers and a hadronic section with steel absorbers . The data cover an energy range from 3.7 to 205 GeV . Detailed comparisons of the data and simulation with GHEISHA 8 in the framework of GEANT 3.14 are presented . The measured pion induced shower profiles are well described by the simulation. The total signal ofpions on an energy scale determined from electron measurements is reproduced to better than 3% in various module configurations. After application of weighting functions, determined from Monte Carlo data and needed to achieve compensation, the reconstructed measured energies agree with simulation to about 3%. The energies of hadronic showers are reconstructed with a resolution of about 50%/~E ® 2%. This result is achieved by inclusion of signals from an iron streamer tube tail catcher behind the liquid argon stacks . 0168-9002/93/$06 .00 © 1993 - Elsevier Science Publishers B.V. All rights reserved 500 Hl Calorimeter Group I Results from pion calibration runs for Hl 1 . Introduction in section 4. In section 5 we discuss the energy recon- During the years 1989 and 1990 several calibration struction first on the e.m. scale defined by electron runs with different modules of the H 1 liquid argon calibration and then on the hadronic energy scale. (LAO calorimeter were performed at the H6 beam Event selection criteria are given in section 6 . Experi- at the CERN SPS. The main goals ofthese runs were mental data and simulation are compared in section 7 to provide an energy calibration for electrons [ 1 ] in for several calorimeter modules in various test config- the H 1 detector [2 ], to study electron-hadron separa- urations. Results are presented for the total energy on tion [3 ] and to determine energy calibration functions the e.m . scale and after full reconstruction of weighted for hadrons andjets. hadronic energy, the achieved energy resolutions, the In previous papers [4,5 ] we reported on the perfor- effective electron-to-pion signal ratio, the longitudinal mance ofprototype LAr test modules . Here we present and lateral shower profiles and on signal distributions results achieved with final modules actually used in the in single channels . H 1 experiment at HERA- The emphasis is put on the comparison of pion signals from calibration measure- 2. Hl liquid argon calorimeter ments with corresponding simulations. This includes The H1 LAr calorimeter at HERA covers an an- results for the fully reconstructed pion energy obtained gular range of 4° ~ 9 ;~ 154°, where 0 is measured with the H 1 standard energy reconstruction code as with respect to the proton axis at HERA (fig. 1) . The used in the actual experiment, running on experimen- calorimeter consists of 8 wheels which are divided in tal and simulated signals from test beam events with- azimuth into 8 modules (octants) in the barrel and out any further change . into 2 modules in the forward region . The modules The Hl calorimeter is non-compensating (i.e. the are divided into an inner, e.m. lead/LAr stack (EMC) signals from electrons are on average higher than those and an outer, hadronic steel/LAr stack (HAC) . The from pions of the same energy), but its high segmen- depth of the EMC varies between 30 radiation lengths in forward 20X0 tation allows to distinguish electromagnetic (e.m. ) (X0) the and in the central barrel part corresponding 1 .4 1 .0 and hadronic shower components and to reconstruct to and interaction lengths (A) the hadronic energies by applying weighting func- for hadrons . The total depth for hadrons including the tions (as discussed first in ref. [6] ) to the measured EMC is in the forward region of IF and FB/OF 6 and and .1 in barrel (CB) . signals . The determination of such functions mainly 8A respectively near 5 the region The calorimeter highly segmented in both the from experimental data has already been studied by is e.m. and hadronic sections of the modules with a total the H1 Calorimeter Group [4,5,7-9] .The quality of of around 45 000 geometric cells in a quasi projective the Monte Carlo predictions for pion test data in the geometry (fig. 1) . The EMC has a 3 or 4 fold longi- H 1 calorimeters [ 10-14 ] now allows for extensive use tudinal segmentation while the HAC has 4 to 6 longi- of simulations for the determination ofthe parameters ofthese functions [ 111 . In this paper we first compare in various module configurations simulation and data for the mean total signal and other quantities char- FB ('B acterizing the details of the shower development . We _.. nom G.111111~~ . then study the deviations on the total hadronic energy "..~ 11111 o weighting AME reconstructed after having applied the same ma-1=2 a-mi-M-jaa.,lm1! 11! _ :. .. 1111 NI !i functions to experimental and simulated data. e~_ °-sE k~ The outline ofthe paper is as follows: In sections 2 and 3 we briefly review the main features of the H 1 test LAr calorimeter and the experimental setup in the [rit-ction Point beam including the iron streamer tube tail catcher . The Monte Carlo simulation procedure is described ____: 111ÎÎ11Î1Î " 1111111111 1IÏ1111ÏI1IIiii0 4- M M 11 ~ ~."0 ElmElm~ t Deceased. 1 . Supported by the Bundesministerium für Forschung rin and Technologie, Germany, under contract numbers 6AC17P, 6AC47P, 6DO57I, 6HH27I, 6MP17I, and Fig . 1 . Schematic view of the wheel and cell structure of the 6WT87P, respectively, HI liquid argon calorimeter with inner forward (IF) and Supported by the UK Science and Engineering Research outer forward (OF) wheels, the forward and central barrel Council. wheels (FB and CB respectively) and the backward barrel t Supported in part by USDOE grant e.m . wheel (BBE). The lines from the interaction point indi- DEF603 91 ER40674 . cate the directions of flight of the particles in the test beam tt Supported by the Swiss National Science Foundation . setup for the different calibration modules discussed here .