Physics Letters B 744 (2015) 391–394
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Analysing powers and spin correlations in deuteron–proton charge
exchange at 726 MeV
S. Dymov
a,b,∗
, T. Azaryan
b
, Z. Bagdasarian
a,c
, S. Barsov
d
, J. Carbonell
e
, D. Chiladze
c,a
,
R. Engels
a
, R. Gebel
a
, K. Grigoryev
a,d
, M. Hartmann
a
, A. Kacharava
a
, A. Khoukaz
f
,
V. Komarov
b
, P. Kulessa
g
, A. Kulikov
b
, V. Kurbatov
b
, N. Lomidze
c
, B. Lorentz
a
,
G. Macharashvili
c,b
, D. Mchedlishvili
c,a
, S. Merzliakov
a,b
, M. Mielke
f
,
M. Mikirtychyants
a,d
, S. Mikirtychyants
a,d
, M. Nioradze
c
, H. Ohm
a
, D. Prasuhn
a
,
F. Rathmann
a
, V. Serdyuk
a
, H. Seyfarth
a
, V. Shmakova
b
, H. Ströher
a
, M. Tabidze
c
,
S. Trusov
h,i
, D. Tsirkov
b
, Yu. Uzikov
b,j
, Yu. Valdau
d,k
, C. Weidemann
l
, C. Wilkin
m
a
Institut für Kernphysik and Jülich Centre for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany
b
Laboratory of Nuclear Problems, JINR, RU-141980 Dubna, Russia
c
High Energy Physics Institute, Tbilisi State University, GE-0186 Tbilisi, Georgia
d
High Energy Physics Department, Petersburg Nuclear Physics Institute, RU-188350 Gatchina, Russia
e
Institut de Physique Nucléaire, Université Paris-Sud, IN2P3–CNRS, F-91406 Orsay Cedex, France
f
Institut für Kernphysik, Universität Münster, D-48149 Münster, Germany
g
H. Niewodnicza´nski Institute of Nuclear Physics PAN, PL-31342 Kraków, Poland
h
Institut für Kern- und Hadronenphysik, Forschungszentrum Rossendorf, D-01314 Dresden, Germany
i
Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, RU-119991 Moscow, Russia
j
Department of Physics, M.V. Lomonosov Moscow State University, RU-119991 Moscow, Russia
k
Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, D-53115 Bonn, Germany
l
University of Ferrara and INFN, I-44100 Ferrara, Italy
m
Physics and Astronomy Department, UCL, Gower Street, London, WC1E 6BT, UK
a r t i c l e i n f o a b s t r a c t
Article history:
Received
2 March 2015
Accepted
9 April 2015
Available
online 15 April 2015
Editor: V.
Metag
Keywords:
Neutron–proton
charge exchange
Polarised
deuterons
Polarised
protons
The charge exchange of vector polarised deuterons on a polarised hydrogen target has been studied in
a high statistics experiment at the COSY-ANKE facility at a deuteron beam energy of T
d
= 726 MeV. By
selecting two fast protons at low relative energy E
pp
, the measured analysing powers and spin corre-
lations
are sensitive to interference terms between specific neutron–proton charge-exchange amplitudes
at a neutron kinetic energy of T
n
≈
1
2
T
d
= 363 MeV. An impulse approximation calculation, which takes
into account corrections due to the angular distribution in the diproton, describes reasonably the de-
pendence
of the data on both E
pp
and the momentum transfer. This lends broad support to the current
neutron–proton partial wave solution that was used in the estimation.
© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
It is a consequence of the nucleon spins that, assuming charge
independence, five complex amplitudes are needed to describe
neutron–proton elastic scattering [1]. This means that, above the
pion production threshold, at least nine independent measure-
ments
are required at each scattering angle to allow an unambigu-
ous
partial wave decomposition. Some of the resulting observables,
which could depend on up to three spin projections [2], are dif-
*
Corresponding author at: Institut für Kernphysik and Jülich Centre for Hadron
Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany.
E-mail
address: s.dymov@fz-juelich.de (S. Dymov).
ficult to determine and values may only be obtained indirectly
through combinations of other measurements.
It
was shown several years ago [3] that, at small momen-
tum
transfers between the deuteron and the diproton, the tensor
analysing power in the deuteron charge exchange on hydrogen,
dp →{pp}
s
n, is closely linked to the spin transfer in neutron–
proton
large angle scattering,
pn →
np, provided that the excita-
tion
energy E
pp
in the final diproton is very low. Due to the Pauli
principle the two protons are then dominantly in the
1
S
0
state
with antiparallel spins, here denoted by {pp}
s
, so that there is then
a spin–isospin flip to this state from the initial deuteron.
http://dx.doi.org/10.1016/j.physletb.2015.04.019
0370-2693/
© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.