Wa80 multiplicity results at 200 A GeV

NuclearPhysics A525 (1991)G57c-660~ North-Holland, Amsterdam

657c

WA80 MULTIPLICITY RESULTS AT 200 A GeV

WA80 - collaboration A Eklundl, J IdhI, R Albrecht*, T C Awes3, C Baktash3, P Beckmann4, F Berger4, R Bock2, G Claessonlv G Clewing4, L Dragon4, R Ferguson3, A Franz5r6, S I A Garpmanl, R Glasow4, H-A Gustafssonl, H H Gutbrod*, P Jacobs5, K-H Kampert4, B W Kolb*, P Kristiansson1r5,I Y Lee3, H Lijhner4sa, I Lund*, F E 0benshain3r6, A Oskarssonl, I Otterlundl, T Peitzmann4, S Persson', F Plasi13, A M Poskanzers, M Purschke4, H-G Ritter5, S Saini3, R Santo4, H R Schmidt*, T Siemiarczuk2rb,S P Sorensen3s6, K Steffens4, E Stenlundl, D Stiiken4,M L Tincknel13 and G R Young3

1) Division of Cosmic and Subatomic Physics, Dept of Physics, University of Lund, SGlvegatan 14, S-223 62 Lund, Sweden

2) Gesellschaft fiirSchwerionenforschung(GSI), Planckstr 1, Postfach 110541, D-6100 Darmstadt, Fed Rep of Germany 3) Oak Ridge National Laboratory (ORNL), POB 2008, Oak Ridge, TN 37831-6372, USA 4) Inst fiirKernphysik, University of Miinster,Wilhelm-Klemm Str. 9, D-4400 Mlinster,Fed Rep of Germany 5) Nuclear Science Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA 6) University of Tennessee, Knoxville, TN 37996-1200, USA a) Now at KVI, University of Groningen, NL-9747 AA Groningen, The Netherlands b) On leave of absence from the Inst for Nuclear Studies, Hoza 69, Pl-00-681, Warsaw, Poland

Multiplicity results are presented from the WA80 setup at CERN. Pseudorapidity, n, and multiplicity distributions from 32S induced reactions in the interval -1.7<~<4.0 are shown. The role of low energy protons in p+A interations is investigated using the Plastic Ball detector covering -1.7<~<1.0 and the Midrapidity Calorimeter (MIRAC) in the interval 2.4
1. THE DETECTOR SYSTEM The detectors1 used for the multiplicity analysis are the Plastic Ball and double layers of streamer tube detectors. The Plastic Ball consists of 655 A&E scintillator telescopes and the streamer t&e detectors are equipped with 43000 pads for readout. Together they cover the full azimuth in the pseudorapidity, Q=lntan(8/2), interval -1.71.4 there are only the streamer tube detectors.

2. THE ANALYSIS The trigger cuts are made by means of a Zero Degree Calorimeter (ZDC). The WA80 minimum bias trigger is defined as less than 86% of the beam energy seen in

0375-9474/91/$03.50 0 1991- Elscvier Science Publishers B.V. (North-Holland)

658~

A. Eklund

32S

et al. / WA80 multiplicity

Au. * Aa.

-t-

WA80 70 0

Cu.

-I’

80

preliminory

results at 200 A GeV

Al at eeeee

Au

A GeV

*e*ee*e

*eee

*e e

e

minimum

bias

ty distributions Pseudorapidi interval -1. 7<)7<4.0.

for

32S +

200

data

Au,

FIGURE 1 32S + Al, Cu, Ag.

Aq,

Cu,

Al at

interactinns

200

@ + F +

m

$

Q

5

c

$

?

8

10-I

minimum

the

A GeV

*

*

in

+

n cu oAl

a

bias

+

+

Tczti I

10-2

,

I 100

Charged

Multiplicity -1.JOK4.0.

distributions

200

multiplicity

for

t I 300

nch in

the

FIGURE 2 32S + Al, Cu, Ag,

I

I

,

400

500

interval

I

't, 0

-1.7<~<4.06

Au interactions

in

the

interval

659~

A. Eklund et al. / WA80 multiplicity results at 200 A GeV

the

ZDC and at

lest

one charged

particle

measured

in

the

streamer

tube

detectors. Corrections applied

to

corrected modules

for. have

therefore this

for

multihit

the data.

However fired

region

will

an enhancement

in

the

in high

somewhat

efficiency

effects,

The production

cause

forward

It

showers n=1.5.

is

part

is

of

in the

events also

hitting It

and acceptance

particles

multiplicity

uncertain.

around

of

Plastic

Ball

and the yield

possible

that

the streamer

being

losses

the streamer

studied

tubes almost

around

particles

tubes.

been

has

been

all n=l.Z-1.4

produced

This

and the data

have

effect

are

is

in

can

cause

still

preliminary. The multihit streamer

tube

effects

The pseudorapidity distribution

3.

are

detectors

in

quite

severe

and we have distribution

figure

in

the extreme

restricted is

shown in

measured

figure

region

to

the

of

region

the n<4.0.

1 and the multiplicity

2.

PRODUCTIONOF PROTONS WITH ENERGIES 20-300 We have

forward

our analysis

the number of

identified

in

the

Plastic

Ball

dependence

of

N, on the

target

in

MeV IN p+A COLLISIONS

low energy

(20-300

the

region

target

mass we see

in

figure

MeV) protons, -1.7
1.0. there

N,, If

we study

is

a linear

p +- Nucleus WA80

A-dependence of the interval -1.7
prelimin:if-y

identified

proton

doto

FIGURE 3 yield in p+A collisions

measured

in

the

the

66Oc

A. Eklund et al. / WA80 multipliciry results at 200 A GeV

dependence

between

calculation

of

background N, is

correction belived

encounters select

and the

We have

central

condition

way through

collisions. samples

is

the

target

the

Midrapidity

the

most

compared

region

(5.1

of

with

the

nucleus figure at

requires

power

2/3.

protons

due

In

the

to

the

large

4 are

our

the

projectile be used

the E, distributions

ten

crossection).

2.4<~<5.5.

behind

that therefore

to

for

200 GeV. The minimum bias

It

the ET-distribution lie

nucleons

and might

more than

the minimum bias covering

will

the

zero

the number of

target in

% of

to

bin.

to one which

it

A, with

p + Au collisions

collisions part

mass,

the bin

Displayed

of

Calorimeter

central

a substantial

this

to be connected

on its

two different

for

target

omitted

The E,

should

will

identified

protons is

be observed

be pushed

in

measured

by

that

for

back

that

and a sample

with

so

far

coverage.

p -I-Au 200 GeV

E, distributions N,>lO. The E,

is

in p+Au collisions for a minimum bias measured in the interval 2.4
REFERENCES 1)

H.H.

Gutbrod

et

al.,GSI-report

GSI-85-32(1985).

sample