Proc of Intl Conf onultra-re1ativistic Nucleus-Nucleus Collisions Quark Matter 97 Tsukuba Japan Dec 1 -5 1997 in press t

The PHENIX Experiment at RHIC

BNL- 6 53 8 5

DP Morrison4 for the PHENIX Collaboration Y Akiba16 0 Alford M Allen W Allen G Alley Y D Autrey20 TC Awes C Barlag25 J J B e h r e n d ~ ~ ~ S Belikov13 S Bellavia S Belyaev MJ B e ~ m e t t ~ ~ ~ ~ ~ Y Berdnik~v~ J Bemardiu21 DD Bluhm14 C EM B ~ h n e ~ ~ JG Boissevainl E B ~ s z e ~ gt ~ l J Bowers20 J BranningO CL Britton ML Brooks21 WL Bryan D B ~ c h e r ~ H B~esching~ V Bumazhn~v ~~ G Bunce S Butsyk2 M Cafeuroerty TA Careyl P Chand J C h a ~ g ~ W-C Chang R Chappell SK Charagi LL C h a ~ e z ~ S Cherni~henko~~ C-Y Chi J Chiba16 A Chikanian43 RK Choudhuy MS C h ~ n g ~ ~ ~ V Cianciolo D Clark2 A Cla~ssen~ S B Cole R Conway L Cope21 D crookg H CuuitzS R Cunninghaml SQ Daniel G David A Denisovl3 EJ Desmond 0 Dietz~ch~ BV Dinesh S D~rrant~ A Durum13 D Dum YV E h e n k o S Eiseman MS Emery K Eno~awa~ H E n ~ o ~ gt ~ ~ MN Ericson V E v s e e ~ ~ J F e m e ~ a ~ ~ DE Fields27 K Filiimono~~ S F o k i ~ ~ D F ~ n g ~ Z Frae~kel~ SS Frank30 AD Frawley J Fried SY Fung D Gan24 J Gannon S JS Haggerty S Hahn JW HalliwellO H Hamagaki H HaraF6 J Harder A Harvey K H a t a ~ k a ~ R Hayano8 N H a ~ a s h i ~ ~ H Ha~ashi~ R JS Hicks R f i g u ~ h i ~ JC Hill14 THira~o~ R Holmes2o B Hong17 R H ~ t t e r ~ T I~hihara~ M Ikeno16 K Imai19133 M Ir~aba~ M Ippolitov18 M I~hihara~ T I ~ h h w a ~ ~ Y Iwata B J a ~ a k ~ ~ ~ ~ G Jackson C Jacobs D Jaffei2 U Jagadish G James BM Johnson JW Johnson S M Kaneta JH Kang4 M Karin SS Kapoor J Kapustinsky21 K Karadjev18 T Ka tayama~~~ S kat^^ T Ka~aguchi~ WL Kehoe MA Kelley M Kennedy EJ Kennedy A Khanzadee~~ A Khomo~tnikov~ J K ik~ch i~ SY YG Kim$4 WW Kinnisonl PN Kirk22 E Kistenev A Kiy~michi~ S K l h l ~ s i e k ~ ~ C Knapp L K ~ c h e n d a ~ ~ VI K~chetkov~ T Kohama B K ~ m k o v ~ V KOZIOV~ T Ko~lowski~ PJ Kroon L K ~ d i n ~ S K ~ m a r ~ M K ~ r a t a ~ V Kuiatkov2 K Ku~ita~ GS Kyle28 JGLajoie14 ALandran20 ALebedev18 VLebedev18 DMLee KSLee17 SJLee17 MJLeitch QLi12 ZLi7y33 M Libkind20 SX Lin R Lind X Liui7 J L o ~ e ~ CF Maguire YI Makdisi A Makeev13 VV Makeev13 V M a n k ~ ~ ~ Y Mao7133 LJ SK Mark24 D Mark~shin~ R M A Masaikelg T Mat~umoto~ K M~Cabe ~ J McClelland21 PL McCaugheyl R M ~ G r a t h ~ ~ DE M~Millan~ JA Mead E Melnikov13 Y Miake39 N Miftakh~v~ TJ Miller A C Moms DP Momson LJ Momson C Mo~cone~ JM Moss ST Mulhall L MUllinsO MM S Nagamiya16 Y Nagasaka6 JL Nagle Y Nakadalg T Nayamp JA S Nishi~nura~ JW NO^^ A Nianiuel8 F Obenshain0136 E OBrien P OConnor H Ohnishi ID V 0nuchinl3 A Oskar~son~ L O~terman~~ I O t t e r l ~ n d ~ ~ K O ~ a m a ~ L PalTi~th~ R Palmer C V Papavassiliou8 JH Park44 B Pasmantirer2 SF Pate8 A Patwa P C Pearson T Pe i t~ raann ~~ V Penmetcha V Perevoztchikov6 R Petersen20 G Petittl0 A Pehidi~ ~ RP Pi~ani4gt~9 P Pitukhinl3 F PlasilO M P o l l a ~ k ~ ~ ~ K Pope36 A Posey R Prigl ML Purschke Y Qi24 DE Quigley14 S Rankowitz GS Rae I Ravinovich2 K Y Riabov2 V Riabov2 G Richardson SH Robinson J R ~ m a n s k i ~ ~ M Rosati~~~~ E R ~ s c h i n ~ AA Rose SS R ~ U ~ N Sait03~ T SakagU~hi~ A Sakaguchi Y Sakemi33337 H Sak03~ T Sakuma33gt37 S Sal~rnone~ V Samsonov2 C Sangster R H S a t ~ h ~ H Schlaghecl~~~ BR Schlei R Schleuter J S~hmid t ~ V Semenov13 R Seto TK Shea I Shein13 V Shelikhov13 T-A S h i b a k ~ ~ ~ ~ K Shigakii6 T Shiina T Shim-39 I SibiriaklS KS sim7 J Simon-Gillo ML Simpsono CP Singh V Shgh FW Sippach HD Skank14 GA Sleege14 N S m i r n ~ v ~ DE Smith3o G Smith MC Smith R Smith W Smithg K Soderstr~rn~ S S ~ e d i n g ~ A S ~ l d a t o v ~ ~ G S o l O d o ~ ~ ~ WE Sondheim21 SP Soren~en~~ PW Stankus N Starin~ki~ E StenI~nd~ D S t ~ e k e n ~ W Stokes SP Stoll R S t o t ~ e r ~ ~ T Sugitate JP Sullivan21 Y su i Z Sun T S v e n ~ s o n ~ ~ EM Takag~ i~ Y Takahashi Y Tampatal A Tampta~i33 KH Tamp6 Y Tanaka6 E T a n i g u ~ h i ~ ~ ~ ~ MJ Tannenbaum V Tarakan~v~ 0 Tarasenkova2 0 Teodores~u ~~ S Tex~hi~ J Thomas2o JL A Tsvetkov18 SK Tuli K hug12 GW hner N lgUrinl3 B Uppiliappan S U r a ~ a w a ~ ~ A Usachev13 H U ~ O ~ C V a 2 9 RI Vandermolen A Vasiliev18 T Vercelli2deg W Verhcmer12~ A V i i o g r a d o ~ ~ ~ V Wshevskii2 R A Vorobyov2 E Vmuzda~~ N Wagner9 JW Walker II Z-F Y Wata~~abe~ X Wei2 SN white D Whitehouse V Wfi-on AL Wintenberg C Wtzig FK Wohnl4 DM W ~ l f e ~ BG Wong-Swansonl W Wong o CL Woody$ J WriW3 H WuF3 M x i a ~ ~ ~ G Xu K Yagi9 R Yamamoto Y A Yokoro Y Y ~ k o t a ~ ~ GR Young WA Zajc8 L Zhang S Z ~ O U ~ Q Zhu and C Z0u5 a

JB Archuleta21 JR Archuleta21 SH Aronson$ I Atatekir~~ B B a s s a l l ~ k ~ S Bathe5 Y B a ~ g i n ~ V Baublis2 A Bazi lev~ky~~ R Begayg

TF Gee B Gim Y SV Greene SK Gupta W Guryn H-A G~stafsson~ Y Gutnikov13

XC Hel0 HW van Hecke21 N HeineF5 S Held6 TK Hemmi~k~ M Hibino

RG Jonesl JP JonesJr S Kahn YA Kamyshkov A Kandasamy$

K Minuzzo JT Mitchell Y Miyam~to~ 0 Miyamural AK Mohanty M Montag JA Moore MS Musrock

L Nikkiner~~ S Nikolaev18 P Nil~son~ M O k a r n ~ ~ ~ V P a n t u e ~ ~ ~

K R e ~ g e r s ~

0 Sasaki HD Satolg S

TL WD T h ~ m a s ~ W Tian$v7 T T~minaka~ S Tense H Toriilg A Trivd I Ts-ya2

M V O ~ ~ O V ~ ~

collaborating ~nstitutions University of Alabama Huntsville AL 35899 USA Banaras Hindu University Varanasi INDIA Bhabha Atomic Research Centre Bombay 400 085 INDIA Brookhaven National Laboratory Upton NY 11973-5000 USA University of California - Riverside Riverside CA 92521 USA Center for Nuclear Study University of Tokyo Tanashi-shi Tokyo 188 JAPAN

2

China Institute of Atomic Energy Beijing P R CHINA Columbia University New York NY 10027 and Nevis Laboratories Irvington NY 10533 USA Florida State University Tallahassee FL 32306 USA

lo Georgia State University Atlanta GA 30303 USA l1 Hiroshima University Kagamiyama Higashi-Hiroshima 739-8526 JAPAN l2 Institute of High Energy Physics Academia Siuica Beijiig 100039 CHINA l3 Institute for High Energy Physics Protvino 142284 Moscow region RUSSIA l4 Iowa State University and Ames Laboratory Ames IA 5001 1 USA l5 Joint Institute for Nuclear Research 141980 Dubna Moscow Region RUSSIA l6 KEK High Energy Accelerator Research Organization Tsukuba-shi Ibaraki-ken 305 JAPAN l7 Korea University Seoul 136-701 KOREA l8 Kurchatov Institute RU-123182 Moscow RUSSIA l9 Kyoto University Kyoto 606 JAPAN 2o Lawrence Livermore National Laboratory Livermore CA 94550 USA 21 Los Alamos National Laboratory Los Alamos NM 87545 USA 22 Louisiana State University Baton Rouge LA 70803 USA 23 Lund University Box 118 SE-22100 Lund SWEDEN 24 McGill University Montreal Quebec H3A 2T8 CANADA 25 Institut h e r Kemphysik University of Muenster D-48149 Muenster GERMANY 26 Nagasaki Institute of Applied Science Nagasaki-shi Nagasaki JAPAN 27 University of New Mexico Albuquerque NM USA 28 New Mexico State University Las Cruces NM 88003 USA 29 State University of New York - Stony Brook Stony Brook NY 11794 USA 30 Oak Ridge National Laboratory Oak Ridge TN 37831 USA 31 Peking University Beijing 100871 CHINA 32 PNPI St Petersburg Nuclear Physics Institute Gatchjna Leningrad RUSSIA 33 The Institute of Physics and Chemical Research (RIKEN) Wako Saitama 351-01 JAPAN 34 St Petersburg State Technical University St Petersburg RUSSIA 35 Universidade de Sao Paulo Instituto de Fisica Sa0 Paulo cp20516-OlOOO BRAZIL 36 University of Tennessee Knoxville TN 37996 USA 37 Tokyo Institute of Technology Tokyo JAPAN 38 University of Tokyo Tokyo JAPAN 39 University of Tsukuba Tsukuba Ibaraki 305 JAPAN 40 Vanderbiit University Nashville TN 37235 USA 41 Waseda University Advanced Research Institute of Science and Engineering 3-4-1 Okubo Shinjuku-ku Tokyo 169-8555 JAPAN 42 Weizmann Institute Rehovot 76100 ISRAEL 43 Yale University New Haven CT 06520-8124 USA 44 Yonsei University Seoul 120-749 KOREA 45 present address University of Arizona Tucson AZ 85721 USA 46 present address Lawrence Berkeley National Laboratory Berkeley CA 94720 USA

This r e s e a r c h supported i n p a r t by the US Department of Energy under Contract DE- 02-98CH1088 ~e physics empkases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented

1 Physics and Design Aims

The primary goals of the heavy-ion program of the PHENIX collaboration are the detection of the quark-gluon plasma and the subsequent characterization of its physical properties To address these aims PHENIX will pursue a wide range of high energy heavy-ion physics topics The breadth of the physics program represents the expectation that it will require the synthesis of a number of measurements to investigate the physics of the quark-gluon plasma The broad physics agenda of the collaboration is also reflected in the design of the PHENIX detector it- self which is capable of measuring hadrons leptons and photons with excellent momentum and energy resolution PHENIX has chosen to instrument a selective acceptance with multiple detector technologies to provide very discriminating particle identification abilities Addition- ally PHENIX will take advantage of RHICs capability to collide beams of polarized protons

lvisit httpllwwwrhicbnlgovlphenix for the most current PHENIX information

2

China Institute of Atomic Energy Beijing P R CHINA Columbia University New York NY 10027 and Nevis Laboratories Irvington NY 10533 USA Florida State University Tallahassee FL 32306 USA

lo Georgia State University Atlanta GA 30303 USA l1 Hiroshima University Kagamiyama Higashi-Hiroshima 739-8526 JAPAN l2 Institute of High Energy Physics Academia Siuica Beijiig 100039 CHINA l3 Institute for High Energy Physics Protvino 142284 Moscow region RUSSIA l4 Iowa State University and Ames Laboratory Ames IA 5001 1 USA l5 Joint Institute for Nuclear Research 141980 Dubna Moscow Region RUSSIA l6 KEK High Energy Accelerator Research Organization Tsukuba-shi Ibaraki-ken 305 JAPAN l7 Korea University Seoul 136-701 KOREA l8 Kurchatov Institute RU-123182 Moscow RUSSIA l9 Kyoto University Kyoto 606 JAPAN 2o Lawrence Livermore National Laboratory Livermore CA 94550 USA 21 Los Alamos National Laboratory Los Alamos NM 87545 USA 22 Louisiana State University Baton Rouge LA 70803 USA 23 Lund University Box 118 SE-22100 Lund SWEDEN 24 McGill University Montreal Quebec H3A 2T8 CANADA 25 Institut h e r Kemphysik University of Muenster D-48149 Muenster GERMANY 26 Nagasaki Institute of Applied Science Nagasaki-shi Nagasaki JAPAN 27 University of New Mexico Albuquerque NM USA 28 New Mexico State University Las Cruces NM 88003 USA 29 State University of New York - Stony Brook Stony Brook NY 11794 USA 30 Oak Ridge National Laboratory Oak Ridge TN 37831 USA 31 Peking University Beijing 100871 CHINA 32 PNPI St Petersburg Nuclear Physics Institute Gatchjna Leningrad RUSSIA 33 The Institute of Physics and Chemical Research (RIKEN) Wako Saitama 351-01 JAPAN 34 St Petersburg State Technical University St Petersburg RUSSIA 35 Universidade de Sao Paulo Instituto de Fisica Sa0 Paulo cp20516-OlOOO BRAZIL 36 University of Tennessee Knoxville TN 37996 USA 37 Tokyo Institute of Technology Tokyo JAPAN 38 University of Tokyo Tokyo JAPAN 39 University of Tsukuba Tsukuba Ibaraki 305 JAPAN 40 Vanderbiit University Nashville TN 37235 USA 41 Waseda University Advanced Research Institute of Science and Engineering 3-4-1 Okubo Shinjuku-ku Tokyo 169-8555 JAPAN 42 Weizmann Institute Rehovot 76100 ISRAEL 43 Yale University New Haven CT 06520-8124 USA 44 Yonsei University Seoul 120-749 KOREA 45 present address University of Arizona Tucson AZ 85721 USA 46 present address Lawrence Berkeley National Laboratory Berkeley CA 94720 USA

This r e s e a r c h supported i n p a r t by the US Department of Energy under Contract DE- 02-98CH1088 ~e physics empkases of the PHENIX collaboration and the design and current status of the PHENIX detector are discussed The plan of the collaboration for making the most effective use of the available luminosity in the first years of RHIC operation is also presented

1 Physics and Design Aims

The primary goals of the heavy-ion program of the PHENIX collaboration are the detection of the quark-gluon plasma and the subsequent characterization of its physical properties To address these aims PHENIX will pursue a wide range of high energy heavy-ion physics topics The breadth of the physics program represents the expectation that it will require the synthesis of a number of measurements to investigate the physics of the quark-gluon plasma The broad physics agenda of the collaboration is also reflected in the design of the PHENIX detector it- self which is capable of measuring hadrons leptons and photons with excellent momentum and energy resolution PHENIX has chosen to instrument a selective acceptance with multiple detector technologies to provide very discriminating particle identification abilities Addition- ally PHENIX will take advantage of RHICs capability to collide beams of polarized protons

lvisit httpllwwwrhicbnlgovlphenix for the most current PHENIX information

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government Neither the United States Government nor any agency thereof nor any of their empioym makes any warranty express or implied or assumes any legal liability or responsibility for the accuracy completeness or use- fulness of any information apparatus product or process disclosed or represents that its use would not infringe privately owned rights Reference herein to any spc- cific commercial product process or service by trade name trademark manufac- turer or otherwise docs not necessarily constitute or imply its endorsement m m - mendation or favoring by the United States Government or any agency thereof The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof

3

with a vigorous spin physics program a subject covered in a separate contribution to these proceedings[ 11

The first measurements PHENIX will make will be of global event properties such as charged particle multiplicity ET production the (pl) of charged particles and fluctuations in these quantities Charged particle multiplicity and ET alone or in correlation with zero-degree calorimetry will provide information about the geometry of each collision From these data one can also deduce the energy density achieved in each event The geometry of the collision charge particle multiplicity ET and energy density may all be used to classify events for other analyses

PHENIX will study many proposed signatures of the deconfinement transition and the restora- tion of chiral symmetry The first of these the deconfinement transition should produce a num- ber of signals observable in the PHENIX detector For instance the suppression of J$ and $rsquo production relative to that of the T will yield information about the strength of Debye screening in the deconfined plasma Measuring J$ suppression relative to the Drell-Yan continuum will allow comparisons with current results such as those from NA50[2] Comparison of charmo- nium production relative to that of open charm-primarily identified through the semi-leptonic decay of charm mesonswill allow PHENIX to disentangle initial state effects such as gluon shadowing from the later dissolving of any created charmonium The many DD pairs that are expected in central Au+Au collisions will also give PHENIX a solid base from which to inves- tigate open charm enhancement in the quark-gluon plasma

An examination of chiral symmetry restoration will complement the study of deconhement The in-medium modification of meson properties due to the restoration of chiral symmetry is predicted to cause changes in the mass and width of the (J meson Since the mass of the 4 meson is only 33 MeV greater than twice the charged kaon mass changes in its properties will also affect the relative branching ratio of (J mesons decaying via KfK- or e+e- channels

The thermal history and available degrees of freedom will be studied through direct y pro- duction and y + e+e- p+p- channels Photons like leptons are unperturbed by the strong interactions that plague hadronic signals and thus retain information about the early history of the collision Whether the colliding system forms a plasma with many degrees of freedom remains a hot hadronic gas or evolves through a long-lived mixed state all have effects on the spectrum of emitted photons Very high p l photons may also serve as a reliable flag for an oppositely directed jet the properties of which may be measured via the leading particle spectrum

The measurement of bosonic or fermionic Hanbury-Brown Twiss correlations and the coales- cence likelihood of various nuclei and anti-nuclei will give insights into the space-time extent and evolution of heavy-ion collisions at RHIC

Enhanced strangeness already a staple feature of relativistic heavy-ion physics will be stud- ied in PHENIX by determining the production cross section of K and 4 mesons This will be complemented by an investigation of enhanced charm production

2 Construction and Current Status of the Experiment

Fundamentally the PHENIX detector consists of a large acceptance charged particle detec- tor and of four spectrometer arms-a pair of spectrometers measuring electrons photons and hadrons which straddles mid-rapidity and a pair of muon spectrometers at forward rapidities-

4

all working together in an integrated manner[3] Each of the four arms has a geometric accep- tance of approximately one steradian The magnetic field in the volume of the collision region is axial while the magnets of the muon arms produce radial fields The PHENIX detector is comprised of eleven different subsystems so that the task of integrating and commissioning the detector is one of the biggest hurdles facing the collaboration

Figure 1 A cutaway drawing of the PHENIX experiment Labeled arrows indicate the major subsystems of the detector

The main sources of event characterization information are the beam-beam counter which consists of two arrays of quartz Cerenkov telescopes surrounding the beam and the multiplicity and vertex detector composed of concentric barrels of silicon strip detectors and end-caps made of silicon pads

uses two technologies for calorimetry lead-scintillator with good timing properties and lead- glass with better energy resolution

The central arm tracking system in PHENIX uses the information provided by several de- tectors Pad chambers yield the three-dimensional space points that are essential for pattern recognition drift chambers provide precise projective measurements of particle trajectories and time-expansion chambers provide r-4 information as well as particle identification Using this tracking information the mass resolution of 4 + e+e- is determined to better than 05 for p l lt 2 GeVlc

Particle identification also hinges on several detectors Panels of time of flight scintillators

Electromagnetic calorimeters are mounted outermost on each of the two central arms PHENIX

c

5

cover part of the central arm acceptance and the 85 ps timing resolution of this time of flight sys- tem separates kaons from pions up to 25 GeVc The timing resolution of the lead-scintillator 280 ps can separate kaons from pions up to about 14 GeVc and its large acceptance greatly improves the rates for measurements such as 4 + K- For electron identification informa- tion from the ring-imaging Cerenkov detector the dEdz measurement of the time-expansion chamber and information from the electromagnetic calorimeter are combined to reject pion contamination of the identified electrons to one part in lo4 over a wide range in momentum

The first part of each muon arm (following a thick hadron absorber) contains three stations of cathode strip tracking chambers The back part of each arm consists of panels of Iarocci streamer tubes alternating with plates of steel absorber The pion contamination of identified muons is below one part in lo4 matching the high degree of confidence in particle identification as is the case with the central arm electron identification The excellent momentum resolution of identified tracks in the muon arms yields a mass resolution of 100 MeVc2 for J$ -+ p+p-

3 Physics Opportunities Grow with Luminosity

During its first two years of operation the luminosity of the RHIC accelerator will gradually ramp up to its full design value In order to make the most effective use of the available lu- minosity the collaboration has developed a plan which matches priorities for physics studies to the anticipated profile of integrated luminosity Early in the first year of RHIC operation when the luminosity will be about 1 of the design value PHENIX will concentrate on mea- surements such as dNhdq dETdq hadronic spectra HBT and inclusive y and TO Each of these measurements can be made with just a few pb- Toward the end of the first year of operation as the luminosity rises to 10 of the design value measurements of q5 -+ KSK- single high p~ leptons and J $ + p+p- become feasible By the end of the first year of RHIC operation PHENE should have seen an integrated luminosity of roughly 100 pb- It is in the second year of RHIC operation as the luminosity reaches its design goal that the full physics program becomes accessible At that point the machine will have sufficient luminosity for measurements of the Drell-Yan continuum open charm production I + pu+p- and J$ and other vector meson decays to ese- The PHENIX spin program also becomes possible in the second year of operation However even this luminosity does not exhaust the PHENIX appetite for physics As the RHIC luminosity improves the horizons of the PHENIX physics program broaden still further

4 Acknowledgements

We thank the technical staffs of the participating institutions for their vital contributions This detector construction project is supported by the Department of Energy (USA) Monbu-sho and STA (Japan) RAS MAE and RMS (Russia) BMBF (Germany) FRN and the Knut amp Alice Wallenberg Foundation (Sweden) and MIST and NSERC (Canada)

REFERENCES

1 N Saito The PHENIX Spin Program These proceedings 2 L Ramello NA3850 Report These proceedings 3 PHENIX Conceptual Design Report BNL 1993 (unpublished)

M98004988 I1lll1111 Ill 111ll lllll111111llll11111111111111111111111

Report Number (14) tu-- hSamp$S

Publ Date (11)

Sponsor Code (1 8) U C Category (1 9)

f 1 7 a

DOE

3

with a vigorous spin physics program a subject covered in a separate contribution to these proceedings[ 11

The first measurements PHENIX will make will be of global event properties such as charged particle multiplicity ET production the (pl) of charged particles and fluctuations in these quantities Charged particle multiplicity and ET alone or in correlation with zero-degree calorimetry will provide information about the geometry of each collision From these data one can also deduce the energy density achieved in each event The geometry of the collision charge particle multiplicity ET and energy density may all be used to classify events for other analyses

PHENIX will study many proposed signatures of the deconfinement transition and the restora- tion of chiral symmetry The first of these the deconfinement transition should produce a num- ber of signals observable in the PHENIX detector For instance the suppression of J$ and $rsquo production relative to that of the T will yield information about the strength of Debye screening in the deconfined plasma Measuring J$ suppression relative to the Drell-Yan continuum will allow comparisons with current results such as those from NA50[2] Comparison of charmo- nium production relative to that of open charm-primarily identified through the semi-leptonic decay of charm mesonswill allow PHENIX to disentangle initial state effects such as gluon shadowing from the later dissolving of any created charmonium The many DD pairs that are expected in central Au+Au collisions will also give PHENIX a solid base from which to inves- tigate open charm enhancement in the quark-gluon plasma

An examination of chiral symmetry restoration will complement the study of deconhement The in-medium modification of meson properties due to the restoration of chiral symmetry is predicted to cause changes in the mass and width of the (J meson Since the mass of the 4 meson is only 33 MeV greater than twice the charged kaon mass changes in its properties will also affect the relative branching ratio of (J mesons decaying via KfK- or e+e- channels

The thermal history and available degrees of freedom will be studied through direct y pro- duction and y + e+e- p+p- channels Photons like leptons are unperturbed by the strong interactions that plague hadronic signals and thus retain information about the early history of the collision Whether the colliding system forms a plasma with many degrees of freedom remains a hot hadronic gas or evolves through a long-lived mixed state all have effects on the spectrum of emitted photons Very high p l photons may also serve as a reliable flag for an oppositely directed jet the properties of which may be measured via the leading particle spectrum

The measurement of bosonic or fermionic Hanbury-Brown Twiss correlations and the coales- cence likelihood of various nuclei and anti-nuclei will give insights into the space-time extent and evolution of heavy-ion collisions at RHIC

Enhanced strangeness already a staple feature of relativistic heavy-ion physics will be stud- ied in PHENIX by determining the production cross section of K and 4 mesons This will be complemented by an investigation of enhanced charm production

2 Construction and Current Status of the Experiment

Fundamentally the PHENIX detector consists of a large acceptance charged particle detec- tor and of four spectrometer arms-a pair of spectrometers measuring electrons photons and hadrons which straddles mid-rapidity and a pair of muon spectrometers at forward rapidities-

4

all working together in an integrated manner[3] Each of the four arms has a geometric accep- tance of approximately one steradian The magnetic field in the volume of the collision region is axial while the magnets of the muon arms produce radial fields The PHENIX detector is comprised of eleven different subsystems so that the task of integrating and commissioning the detector is one of the biggest hurdles facing the collaboration

Figure 1 A cutaway drawing of the PHENIX experiment Labeled arrows indicate the major subsystems of the detector

The main sources of event characterization information are the beam-beam counter which consists of two arrays of quartz Cerenkov telescopes surrounding the beam and the multiplicity and vertex detector composed of concentric barrels of silicon strip detectors and end-caps made of silicon pads

uses two technologies for calorimetry lead-scintillator with good timing properties and lead- glass with better energy resolution

The central arm tracking system in PHENIX uses the information provided by several de- tectors Pad chambers yield the three-dimensional space points that are essential for pattern recognition drift chambers provide precise projective measurements of particle trajectories and time-expansion chambers provide r-4 information as well as particle identification Using this tracking information the mass resolution of 4 + e+e- is determined to better than 05 for p l lt 2 GeVlc

Particle identification also hinges on several detectors Panels of time of flight scintillators

Electromagnetic calorimeters are mounted outermost on each of the two central arms PHENIX

c

5

cover part of the central arm acceptance and the 85 ps timing resolution of this time of flight sys- tem separates kaons from pions up to 25 GeVc The timing resolution of the lead-scintillator 280 ps can separate kaons from pions up to about 14 GeVc and its large acceptance greatly improves the rates for measurements such as 4 + K- For electron identification informa- tion from the ring-imaging Cerenkov detector the dEdz measurement of the time-expansion chamber and information from the electromagnetic calorimeter are combined to reject pion contamination of the identified electrons to one part in lo4 over a wide range in momentum

The first part of each muon arm (following a thick hadron absorber) contains three stations of cathode strip tracking chambers The back part of each arm consists of panels of Iarocci streamer tubes alternating with plates of steel absorber The pion contamination of identified muons is below one part in lo4 matching the high degree of confidence in particle identification as is the case with the central arm electron identification The excellent momentum resolution of identified tracks in the muon arms yields a mass resolution of 100 MeVc2 for J$ -+ p+p-

3 Physics Opportunities Grow with Luminosity

During its first two years of operation the luminosity of the RHIC accelerator will gradually ramp up to its full design value In order to make the most effective use of the available lu- minosity the collaboration has developed a plan which matches priorities for physics studies to the anticipated profile of integrated luminosity Early in the first year of RHIC operation when the luminosity will be about 1 of the design value PHENIX will concentrate on mea- surements such as dNhdq dETdq hadronic spectra HBT and inclusive y and TO Each of these measurements can be made with just a few pb- Toward the end of the first year of operation as the luminosity rises to 10 of the design value measurements of q5 -+ KSK- single high p~ leptons and J $ + p+p- become feasible By the end of the first year of RHIC operation PHENE should have seen an integrated luminosity of roughly 100 pb- It is in the second year of RHIC operation as the luminosity reaches its design goal that the full physics program becomes accessible At that point the machine will have sufficient luminosity for measurements of the Drell-Yan continuum open charm production I + pu+p- and J$ and other vector meson decays to ese- The PHENIX spin program also becomes possible in the second year of operation However even this luminosity does not exhaust the PHENIX appetite for physics As the RHIC luminosity improves the horizons of the PHENIX physics program broaden still further

4 Acknowledgements

We thank the technical staffs of the participating institutions for their vital contributions This detector construction project is supported by the Department of Energy (USA) Monbu-sho and STA (Japan) RAS MAE and RMS (Russia) BMBF (Germany) FRN and the Knut amp Alice Wallenberg Foundation (Sweden) and MIST and NSERC (Canada)

REFERENCES

1 N Saito The PHENIX Spin Program These proceedings 2 L Ramello NA3850 Report These proceedings 3 PHENIX Conceptual Design Report BNL 1993 (unpublished)

M98004988 I1lll1111 Ill 111ll lllll111111llll11111111111111111111111

Report Number (14) tu-- hSamp$S

Publ Date (11)

Sponsor Code (1 8) U C Category (1 9)

f 1 7 a

DOE

4

all working together in an integrated manner[3] Each of the four arms has a geometric accep- tance of approximately one steradian The magnetic field in the volume of the collision region is axial while the magnets of the muon arms produce radial fields The PHENIX detector is comprised of eleven different subsystems so that the task of integrating and commissioning the detector is one of the biggest hurdles facing the collaboration

Figure 1 A cutaway drawing of the PHENIX experiment Labeled arrows indicate the major subsystems of the detector

The main sources of event characterization information are the beam-beam counter which consists of two arrays of quartz Cerenkov telescopes surrounding the beam and the multiplicity and vertex detector composed of concentric barrels of silicon strip detectors and end-caps made of silicon pads

uses two technologies for calorimetry lead-scintillator with good timing properties and lead- glass with better energy resolution

The central arm tracking system in PHENIX uses the information provided by several de- tectors Pad chambers yield the three-dimensional space points that are essential for pattern recognition drift chambers provide precise projective measurements of particle trajectories and time-expansion chambers provide r-4 information as well as particle identification Using this tracking information the mass resolution of 4 + e+e- is determined to better than 05 for p l lt 2 GeVlc

Particle identification also hinges on several detectors Panels of time of flight scintillators

Electromagnetic calorimeters are mounted outermost on each of the two central arms PHENIX

c

5

cover part of the central arm acceptance and the 85 ps timing resolution of this time of flight sys- tem separates kaons from pions up to 25 GeVc The timing resolution of the lead-scintillator 280 ps can separate kaons from pions up to about 14 GeVc and its large acceptance greatly improves the rates for measurements such as 4 + K- For electron identification informa- tion from the ring-imaging Cerenkov detector the dEdz measurement of the time-expansion chamber and information from the electromagnetic calorimeter are combined to reject pion contamination of the identified electrons to one part in lo4 over a wide range in momentum

The first part of each muon arm (following a thick hadron absorber) contains three stations of cathode strip tracking chambers The back part of each arm consists of panels of Iarocci streamer tubes alternating with plates of steel absorber The pion contamination of identified muons is below one part in lo4 matching the high degree of confidence in particle identification as is the case with the central arm electron identification The excellent momentum resolution of identified tracks in the muon arms yields a mass resolution of 100 MeVc2 for J$ -+ p+p-

3 Physics Opportunities Grow with Luminosity

During its first two years of operation the luminosity of the RHIC accelerator will gradually ramp up to its full design value In order to make the most effective use of the available lu- minosity the collaboration has developed a plan which matches priorities for physics studies to the anticipated profile of integrated luminosity Early in the first year of RHIC operation when the luminosity will be about 1 of the design value PHENIX will concentrate on mea- surements such as dNhdq dETdq hadronic spectra HBT and inclusive y and TO Each of these measurements can be made with just a few pb- Toward the end of the first year of operation as the luminosity rises to 10 of the design value measurements of q5 -+ KSK- single high p~ leptons and J $ + p+p- become feasible By the end of the first year of RHIC operation PHENE should have seen an integrated luminosity of roughly 100 pb- It is in the second year of RHIC operation as the luminosity reaches its design goal that the full physics program becomes accessible At that point the machine will have sufficient luminosity for measurements of the Drell-Yan continuum open charm production I + pu+p- and J$ and other vector meson decays to ese- The PHENIX spin program also becomes possible in the second year of operation However even this luminosity does not exhaust the PHENIX appetite for physics As the RHIC luminosity improves the horizons of the PHENIX physics program broaden still further

4 Acknowledgements

We thank the technical staffs of the participating institutions for their vital contributions This detector construction project is supported by the Department of Energy (USA) Monbu-sho and STA (Japan) RAS MAE and RMS (Russia) BMBF (Germany) FRN and the Knut amp Alice Wallenberg Foundation (Sweden) and MIST and NSERC (Canada)

REFERENCES

1 N Saito The PHENIX Spin Program These proceedings 2 L Ramello NA3850 Report These proceedings 3 PHENIX Conceptual Design Report BNL 1993 (unpublished)

M98004988 I1lll1111 Ill 111ll lllll111111llll11111111111111111111111

Report Number (14) tu-- hSamp$S

Publ Date (11)

Sponsor Code (1 8) U C Category (1 9)

f 1 7 a

DOE

c

5

cover part of the central arm acceptance and the 85 ps timing resolution of this time of flight sys- tem separates kaons from pions up to 25 GeVc The timing resolution of the lead-scintillator 280 ps can separate kaons from pions up to about 14 GeVc and its large acceptance greatly improves the rates for measurements such as 4 + K- For electron identification informa- tion from the ring-imaging Cerenkov detector the dEdz measurement of the time-expansion chamber and information from the electromagnetic calorimeter are combined to reject pion contamination of the identified electrons to one part in lo4 over a wide range in momentum

The first part of each muon arm (following a thick hadron absorber) contains three stations of cathode strip tracking chambers The back part of each arm consists of panels of Iarocci streamer tubes alternating with plates of steel absorber The pion contamination of identified muons is below one part in lo4 matching the high degree of confidence in particle identification as is the case with the central arm electron identification The excellent momentum resolution of identified tracks in the muon arms yields a mass resolution of 100 MeVc2 for J$ -+ p+p-

3 Physics Opportunities Grow with Luminosity

During its first two years of operation the luminosity of the RHIC accelerator will gradually ramp up to its full design value In order to make the most effective use of the available lu- minosity the collaboration has developed a plan which matches priorities for physics studies to the anticipated profile of integrated luminosity Early in the first year of RHIC operation when the luminosity will be about 1 of the design value PHENIX will concentrate on mea- surements such as dNhdq dETdq hadronic spectra HBT and inclusive y and TO Each of these measurements can be made with just a few pb- Toward the end of the first year of operation as the luminosity rises to 10 of the design value measurements of q5 -+ KSK- single high p~ leptons and J $ + p+p- become feasible By the end of the first year of RHIC operation PHENE should have seen an integrated luminosity of roughly 100 pb- It is in the second year of RHIC operation as the luminosity reaches its design goal that the full physics program becomes accessible At that point the machine will have sufficient luminosity for measurements of the Drell-Yan continuum open charm production I + pu+p- and J$ and other vector meson decays to ese- The PHENIX spin program also becomes possible in the second year of operation However even this luminosity does not exhaust the PHENIX appetite for physics As the RHIC luminosity improves the horizons of the PHENIX physics program broaden still further

4 Acknowledgements

We thank the technical staffs of the participating institutions for their vital contributions This detector construction project is supported by the Department of Energy (USA) Monbu-sho and STA (Japan) RAS MAE and RMS (Russia) BMBF (Germany) FRN and the Knut amp Alice Wallenberg Foundation (Sweden) and MIST and NSERC (Canada)

REFERENCES

1 N Saito The PHENIX Spin Program These proceedings 2 L Ramello NA3850 Report These proceedings 3 PHENIX Conceptual Design Report BNL 1993 (unpublished)

M98004988 I1lll1111 Ill 111ll lllll111111llll11111111111111111111111

Report Number (14) tu-- hSamp$S

Publ Date (11)

Sponsor Code (1 8) U C Category (1 9)

f 1 7 a

DOE

M98004988 I1lll1111 Ill 111ll lllll111111llll11111111111111111111111

Report Number (14) tu-- hSamp$S

Publ Date (11)

Sponsor Code (1 8) U C Category (1 9)

f 1 7 a

DOE