Study of Deuteron-Deuteron Scattering at 65 MeV/nucleon

Ahmad Ramazani-Moghaddam-Arani(KVI-Cracow-Katowice-IUCF)

19th International IUPAP Conference on Few-Body Problems in Physics 31.08 - 05.09.2009 - University of Bonn / Germany

University of KashanIran

Outline

Three-nucleon forceWhy dd scatteringExperimental setupAnalysis of the break-up channel ResultsSummary

Motivation

How big is the 3NF?Effective field theory, based on PT (low-energy expansion in QCD):

perturbative calculations of the interactions between nucleons with pions as exchange particles.

3N forces smaller than 2NF

4N forces even smaller than 3NF!!

Prediction of 3NF: H. Primakoff et al., Phys. Rev. 55, 1218 (1939)

Sensetive observaablesHigh presition measurements

Motivation

3NF effect is not negligible, and is not completely understood yet!

p + d p +d

use the 4-nucleon system to study 3NF !

Model 3H (MeV) 4He (MeV)

Nucleon-Nucleon 7.62 24.2

GFMC + 3NF 8.47 28.3

Experiment 8.48 28.4

Large sensitivity to 3NP effects exists in the minimum of the differential cross section

H. Witala et al., Phys. Rev. Lett. 81, 1183 (1998).

S. Nemoto et al., Phys. Rev. C 58, 2599 (1998)

4N Calculation Status

Phys. Rev. C 76, 021001(R) (2007)

Deuteron Energy : 3MeV

Below Break-up Threshold

dd Elastic Scattering at 65 MeV/nucleon

Calculation: Deltuva, Fonseca, et al.

Note: lowest-order terms in Born series expansion of the AGS equations

•High energies•Low momentum transfer

Experiment and reaction channels Big Instrument for Nuclear-polarization Analysis

Beam: Polarized deuteronTarget: Liquid deuterium for ddTarget: solid CH2 for dp Beam Energy: 65 MeV/nucleon

Event Selection

Spin Observables

Pure Vector-polarization

Pure tensor-polarization

Three-body Breakup Result

Cross section = (Invariant matrix)2 * (Phase space factor)

42 configurations500 data points

Quasi-free dp elastic scattering in the three-body break-up reaction

d + d d + p + n

d + p d + p

Quasi-free dp elastic result

Data from literature

NN

NN + TM’

Quasi-free dp elastic result

dp elastic from literature

NN

NN + TM’

dp elastic, this work

Quasi-free dp elastic result dp elastic from literature

NN

NN + TM’

dp elastic, this work

Quasi-free dp elastic, this work

Summary and Outlook A few final states of the dd scattering at 65 MeV/nucleon have been identified .

Differential cross sections, vector and tensor analyzing powers for the elastic d+d channel have been measured.

The three-body break-up in dd scattering has been measured in and almost background free experiment.

The quasi-free part of the three-body break-up data in dd scattering can be directly compared with the results of the dp elastic scattering .

Surprisingly, the T20 results of the quasi-free dp show a big discrepancy from the dp elastic scattering .

KVI experiments will provide an extensive database in four-nucleon scattering at intermediate energies.

Theoretical calculations for dd scattering at intermediate energies are called for.

Our Collaborators A. Ramazani-Moghaddam-Arani, H. R. Amir-Ahmadi, A. D. Bacher, C. D. Bailey, A. Biegun, M. Eslami-Kalantari, I. Gašparić, L. Joulaeizadeh, N. Kalantar-Nayestanaki, St. Kistryn, A. Kozela, H. Mardanpour, J. G. Messchendorp, A. M. Micherdzinska, H. Moeini,V. Shende, E. Stephan, E. J. Stephenson, and R. Sworst

Thanks for your attention

dp Elastic Scattering Observables

A. Ramazani-Moghaddam-Arani et al., Phys. Rev. C 78, 014006 (2008)

H. Mardanpour et al., Eur. Phys. J. A 31, 383 (2007).

E. J. Stephenson et al., Phys. Rev. C 60, 061001 (1999).

H. Shimizu et al., Nucl. Phys. A 382, 242 (1982).

dd Elastic Scattering Observables

Calculation: Deltuva, Fonseca, et al.

Note: lowest-order terms in Born series expansion of the AGS equations

Three-body Breakup Result

Cross section = (Invariant matrix)2 * (Phase space factor)

Available data and theories

Theoretical attempts

To solve the four-body system:

1) A. Deltuva et al., Phys. Rev. C 69, 034004 (2004).2) M. Viviani et al., Phys. Rev. Lett. 86, 3739 (2001).3) F. Ciesielski, J. Carbonell, and C. Gignoux, Phys. Lett. B447, 199 (1999).

Calculation of the cross section and spin observables for elastic dd scattering :

4) A.C. Fonseca, Nucl. Phys. A737, S103, (2004).

Summary and outlook• Differential cross section, vector and tensor analyzing powers for elastic channel at forward scattering angles are measured. Reliability of the obtained data is based on the dp elastic scattering results and comparison of the BINA and BBS results. •Three-body breakup channel in the dd scattering at 65 MeV/nucleon has been identified.•The differential cross section for few configurations are measured for the first time at KVI and compared with the phase space result.

Outlook•Measurement of the cross section and analyzing powers for more configurations.•KVI experiments will providing a systematic database, which will be used to test the present and upcoming theoretical calculations.

Theoretical calculations for dd scattering is called for!

Available data and theoriesA. M. Micherdzinske et al, Phys. Rev. C 75, 054001(2007)

Deviation of the data from theory calls for

a systematic measurement of the cross

sections and analyzing powers

Motivation

π0

The observation demonstrates that

CS is broken

is odd under CS

?d

d

4He

Observation provides access to the quark-mass difference mu-md

The results rely on a precise knowledge of the four-nucleon dynamics,in particular the initial-state interaction.

(E. Stephenson et al. Phys. Rev. Lett. 91 (2003) 142302)

Event Selection d + d d + p + n

D

Three-body Break-up Channel

d + d d + p + n

E- DeltaE TOF

Elastic Channel Identification

Three-body Breakup Result

Motivation

Effectieve Field Theorie, based on PT (low-energy expansion in QCD):

perturbative calculations of the interactions between nucleons with pions as exchange particles.

4N forces even smaller than 3NF!!

… use the 4-nucleon system to study 3NF !

Unexplored territory at intermediate energies !!!Unexplored territory at intermediate energies !!!

Nucleon-Nucleon Interaction• The traditional goal of nuclear physics : Understanding the properties of

atomic nuclei in terms of the 'bare' interaction between pairs of nucleons, or nucleon-nucleon forces .

• How to study the NN forces: 1- Attributing a potential to the nucleons and solving the Schrödinger

equation. 2- Performing scattering experiments. 3-Determination of the potential parameters by fitting to the

experimental data .

• Ultimate goal of the nuclear physics: describing all nuclear interactions from the basic interactions between nucleons. This is called the microscopic or ab initio approach of nuclear physics.

The modern NNPs reproduce the world data base with aThe modern NNPs reproduce the world data base with areduced chi-square close to one and have, therefore, beenreduced chi-square close to one and have, therefore, beenaccepted as high-quality benchmark potentials.accepted as high-quality benchmark potentials.

Three-body Breakup Result Model 3H (MeV) 4He (MeV)

Nucleon-Nucleon 7.62 24.2

GFMC + 3NF 8.47 28.3

Experiment 8.48 28.4

dp elastic from literature

NN

NN + TM’

dp elastic, this work

Quasi-free dp elastic, this work