Amherst, Massachusetts, 01003. D.C. Christian, G. Gutierrez, S.D. Holmes, and A.Wehmann. Fermi National Accelerator Laboratory,. Batavia, Illinois 60510.
a
Fermi National Accelerator
Laboratory
FERMILAB-Pub-92/67
Observation of Coulomb Effects in Production of n;+r, and K+ K- Pairs in pp Collisions at 27.5 GeV/c L.R. Wiencke, M.D. Church, E.E. Gottschalk, R.A. Hylton, B.C. Knapp, W. Sippach and B.J. Stern Columbia Univeristy, Neuis Laboratories, Irvington, New York 10533
E.P. Hartouni, D.A. Jensen, B. Klima, M.N. Kreisler, M.S.Z. Rabin, J.B. Strait, and J. Uribe Department
of Physics and Astronomy, Amherst,
University of Massachusetts, Massachusetts, 01003
D.C. Christian, G. Gutierrez, S.D. Holmes, and A.Wehmann Fermi National Accelerator Laboratory, Batavia, Illinois 60510
C. Avilez Institute
de Fisica, Uniuersidad de Guanajuato, Leon, Gto., Mexico
M. Forbush, F.R. Huson and J.T. White Depatiment
of Physics, Terns A & M University, College Staion, Texas 77843
October 1992 Submitted
0
to Physical
Operated by Universities
Review D
Research Association
Inc. under Contract No. DE-AC02-76CH03000
with me United States Department
of Energy
Disclaimer
This report was prepared as an account of work sponsored by an agency of the United States Gouernment. Neither the United States Government nor any agency thereof nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, ‘completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, 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:
To Be Published
in
Physical
Review
D (1992).
Ncvis RW 1477 UMHEP 392 FERMIlAB PUB 92/67
Observation of Coulomb Effects in Production of lt+n-, pn-, and K*K- Pairs in pp Collisions rt 27.5 GcVlc
l
L.R. Wicncke, M.D. Church(a), E.E. Gottschalk, R.A. HyIton(b). B.C. Knapp, W. Sippach, and B.J. Stern(c) University, Ncvis’ Laboratories. Irvington, New York 10533 USA
Columbia
E.P. Hartouni,
M.S.Z. Deparlmenl
D.A. Jensen(e), B. Klimata), M.N. Kreisler. Rabin, J.B. Straitfa), and J. Uribe
df Physics and Astronomy. Amherst, Massachusells
D. C. Christian,
G. Gutierrez. Fermilab,
Batavia,
University of Massachusetts. 01003 USA
S.D. Holmes,
and A. Wehmann
Illinois
USA
60510
C. Avilcz(c) Institute
de Fisica.
Univcrsidsd
M:+er&stie)),
de Guanajualo.
F.R. Huson.
Leon, Gto.. Mexico
and J.T. &hite
Department of Physics, Texas ABM Universily. College Station. Texas 77843 USA
*Funded
in part
PHY89-21320, Contracts CONACyT
by the National PHY90-14879;
No. DE-AC02-76CH03000, de Mexico.
Science
Foundation
the Department
under
of Energy
DE-ASOS-87ER40356;
Grants under and
Abstract In a study
of collisions
have
observed
pairs
when
frame
interaction
(PACS
enhanced
the relative
approaches
enhancement
of 27.5 GeVlc
ac.
agree
production velocity
as described
numbers:
13.85.Hd.
with
in liquid
of oppositely of the two
The scale
well
protons
hadrons
and velocity
the effect
by the Gamow
13.40.K~)
charged
dependence
we
hadron
in the pair
of the attractive factor.
hydrogen
of the Coulomb
ies~
The
electromagnetic
modify
observed
having
relative
interaction
phase
space
velocity,
fi*,
has long
for pairs
densities in their
been
rest frame
of order
effect
is described
by the Gamow
G(q)=ZItq/(e**nl-1).
where
q=a2tZ-2p/qq,
uis
l/m+
+
1 /m-).
Z+and
three-momentum
difference
qccu. R* is simply
q12u.
correction observation
used
reconstructed GeV/c
Gradient
protons
Six
drift
measured magnetic was
in liquid
charged field
GeV/c). hardware
of central
trajectories value
by time-of-flight counter
reconstruction
7.5 kG.
used
production.
Alternating-
a large
l.mm
aperture at high
particle
rates.
to 1..7.mm
in a non-uniform Direct
8
in interactions
interactions
distance
high
on average
produced
hodoscopes (n/K/p
We report
pair
at the BNL
complex
of metimuml-drift particle
foil(o).
containing
766(7)
direct
in x%-pair
in moderately
were
When
The first
and K+K-
hydrogen
Experiment
Cherenkov Track
that
I) to measure
c.hambers
provided
threshold
using
(Fig.
events
and q is the
as an unobservable
interaction
pn-,
mass
of the pair.
studies(s).
effects
This
factor,
charges,
on tantalum
for n+x-,
particles
Sy~nchrotron.
spectrometer
protons
300 million
charged
used
particles
ac(t-4).
reduced
frame
correlation
of Coulomb
pp collisions
We analyzed
has been
state Coulomb
70 GeV/c
the measurement
multiplicity
27.5
pair
of the final
production here
G(q)
in same sign
the
Z- are the particle in the rest
to
of charged
velocity-dependent
( l/u=
predicted
dipole identification
and by a 96-cell
thresholds
was performed
of 2.5/9.0/17.0 by a special
purpose
processor(8).
We investigate
the p’, dependence
quantities
are independent
that
of (+/-) of particle
pairs
at small
fi*
mass assignment.
of
We directly the
pair
measure momentum,
qL, the relative
momentum
and
asymmetry:
Y-(IPr-IP-I)/(IPr+lP-I)
momentum
where
For relativistic
momenta.
P+and
small
perpendicular
P’ are the particles’
opening
angle
to
lab
pairs,
Y=E+!b$ ( )I )I1 For small
a narrow
ql,
provides
a signature
We selected neither
particle
intersecting
assigned
softer
pairs
for the conversion
horizontal
candidates
counter with
as an e+(e-);
identified
as heavier
Fig.
to help
select
2 shows
a pion;
< 250 (MeV/c)2, and both
by at least
particles two
e+e- pairs
These pairs,
from
c+e- pairs
samples:
qx i
100
(J15-lOMeV/c 2 .-a 0 a 150 z Dti 100 E :
50 (J10-5 MeV/c 0 0.65 0.7 0.75
0.8
Y (Data)
0.65
~0.7
0.75
Y (Monte Carlo)
Fig. 4
0.8
Number 8
0
-
of Pairs -
IA0
Per
Y bin L
(1 bin = 0.02) cm0 M i.3
2,
