Antiprotons as Probes for Nuclear Structure Investigations of Exotic Nuclei

H. Lenske Institut für Theoretische Physik, U. Giessen

• Neutron Skins in Exotic Nuclei• Antiproton-Nucleus Interactions• Elastic Scattering• Nuclear Radii from Absorption Cross Sections• Screening of Protons in Neutron-rich Nuclei• Outlook

Neutron Skins in Ni and Sn Isotopes

F. Hofmann et al., PRC64 (2001); N. Tsoneva. H.L., PLB586 (2004) and PRC (2007)

Neutron Skins and PDR Strength in Sn

Isotopes a4=32MeV

a4=26MeV

Measuring Neutron Skins on Isotopic Chains (Ni,Sn…):

p + A Absorption@FAIR: the AIC Proposal

P. Kienle, NMB 214 (2004) and AIC@FAIR

Proposal

H.L., P. Kienle, Phys.Lett. B647 (2007) 82-87

Antiproton-Nucleon Annihilation

pN

pN

t 1

3t

The antiproton-Nucleon Interaction

The antiproton-Nucleus Interaction

Antiproton+A scattering:

• Free Space pN T-Matrix

• Nuclear Structure Input: HFB p and n Densities

• optical Potential in Impulse or t Approximation

Antiproton+Nucleus Interactions:Elastic Scattering

pA Scattering: Optical Potential and Absorption Cross

Section From The Continuity

Equation:

3 ( )† ( )abs s s opt s2

2m 1tr d r r, k (U (r)) r, k

2s 1k

s2 (z,b)2abs s opt2

2m 1tr d bdz (U (r))e

2s 1k

Eikonal Approximation:

Antiproton Absorption on 58,78Ni: The Monopole Annihilation Kernel and the

Nuclear Density

( ) 2s

1 1ˆ(r, k) dr | (r, k) |

2s 1 4

Probing Nuclear Radii by Antiprotons

• scaling of abs ~ <r2>

• energy independent slope

• convergence of magnitude

• increasing <r2>

• from proton to neutron skin

• neutron skins up to 0.6 fm

• charge radii by e- scattering

Measuring Neutron Skins on Isotopic Chains (Ni,Sn…):

p + A Absorption on protons and neutrons

H.L., P. Kienle, Phys.Lett. B647 (2007) 82-87

Antiproton Annihilation on Ni-Isotopes: Scaling of abs

Q1: Antiproton+N Absorption: Isospin Symmetry

ppnp

ppnp

p A(N,Z) A(N 1,Z) k

p A(N,Z) B(N,Z 1) k

Q2: Peripheral Antiproton Annihilation on a Nucleus:

(n) ( ) ( )pN n nM t (x) p (r )

Differential Antiproton Annihilation on a Nucleus:

k k0k k

k

np a b

2 2(n)pN n

n n

d M (q) ~ q

• Microscopic Approach to Antiproton-Nucleus Interactions

• Antiprotons as a Probe for Nuclear Skins

• Screening of the Core Protons in neutron-rich Nuclei

• Exclusive Processes: Studies of A A-1 Reactions

• Multi-Pion and YY Production

• Antiproton In-Medium Interactions:

• Test of G-parity for antiproton-N interactions,

• Study of dispersive self-energies

Summary and Outlook

Together with: Nadia Tsoneva, Urnaa Badarch, P. Kienle

Antiproton Ion Collider (AIC) Collaboration @ FAIR