Antiprotons for Nuclear Structure Investigations H. Lenske Institut für Theoretische Physik, U. Giessen
Feb 02, 2016
Antiprotons for Nuclear Structure Investigations
H. Lenske Institut für Theoretische Physik, U. Giessen
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
Antiprotons for Nuclear Structure Investigations @FAIR
Agenda:
Antiproton-N and Antiproton-Nucleus Antiproton-N and Antiproton-Nucleus InteractionsInteractions
Nuclear Radii from Absorption Cross SectionsNuclear Radii from Absorption Cross Sections Antiprotons and Neutron-SkinsAntiprotons and Neutron-Skins Screening Effects in Neutron-rich NucleiScreening Effects in Neutron-rich Nuclei Isospin Tagging by Pion ProductionIsospin Tagging by Pion Production Strangeness ProductionStrangeness Production OutlookOutlook
The antiproton-proton Interaction: LEAR Data
p p
p p
Antiproton-Nucleon Interactions
KK
p p
...
- 0
0
K K
n p
...
The History of the longterm relation…
…of antiprotons and nuclei:
• anti-protonic atoms and tails of nuclear densities
• antiproton-A elastic scattering
• annihilation and pion production
• G-parity transformation of scalar and vector self-energies deep potentials ~ -500 MeV
• dispersive self-energies from annihilation channels
• Annihilation and Quark Models
• Meson & Hadron Dynamics from pphh
Consequences of G-Parity in Nuclear Binding
Energy Deposition in a Nucleus
(Cascade-Calculations, Clover et al., PRC 26)
p p (at rest)
The antiproton-Nucleus Interaction
Antiproton+A scattering:
• Free Space pN T-Matrix
• Nuclear Structure: state-of-the-art HFB p and n Densities
• optical Potential in Impulse (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, 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
Antiproton+A Absorption: Limiting Cases
Probing Nuclear Radii by Antiprotons
• scaling of abs ~ <r2>
• energy independent slope
• convergence of magnitude
• from proton to neutron skin
• increasing <r2>
• 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
Localization of the Annihilation Process
2
dP(b) (b)
bdb
bk ( 1)
Spatial Localization of Antiproton
Annihilation on a Nucleus:
Peripheral Process
Cascade Results by Clover et al., PRC 26
Absorption on Protons
b=4fm
Absorption on Neutrons
b=4fm
Shielding of Target Protons by the Neutron Skin
protons
neutrons
Tlab=700 MeV
Antiproton Annihilation on Ni-Isotopes: Scaling of abs
Antiproton+N Absorption: Isospin Symmetry
ppnp
ppnp
Antiproton+Nucleus Interactions: Isospin Symmetry
...)()()(
)()()(~)(
2
20
rrkt
rrktrU
pnF
pnFAp
Enhanced along isotopic chains!
p A(N,Z) C(N 1,Z) k
0p A(N,Z) B(N,Z 1) k n
Peripheral Antiproton Annihilation on a Nucleus:
Pion Production:
Differential Coherent Antiproton Annihilation on a Nucleus:
k kk
0
...
KK ...Np a hh
YY ...
... (N=n)
( )*3 3 ( )pN n nM (k ,k ) d r d r (k , r ) t (x) (r ) (k , r )
i(k r k r ) 2 (r , r )3 3pN n nM (k ,k ) ~ d r d r e t (x) (r )e
Differential Antiproton Annihilation on a Nucleus:
Eikonal Approximation:
Quantum Mechanical Amplitude:
LEAR-Data (PS185) on Strangeness Production
DDRH Flavour Dynamics: Single Particle Energies
DDRH Theory: Density Dependent NN and N Dirac-Brueckner Vertices
Nuclear Matter S
= 28 MeV
Phase Space Distribution for pbar+A -> anti-Y+B(Y)+pi^- Target: 40Ca
Lambda 300 200 100
Sigma^0 300 200 100
0100200300400500600700800k(anti-Y) [MeV/c] 100200300400500600700800
q(pi^-) [MeV/c]
050
100150200250300350
d^2P(k,q)/dE(k)dE(q)
Phase Space Distribution for pbar+A -> anti-Y+B(Y)+pi^- Target: 56Ca
Lambda 200 150 100 50
Sigma^0 200 150 100 50
0100200300400500600700800k(anti-Y) [MeV/c] 100200300400500600700800
q(pi^-) [MeV/c]
050
100150200250
d^2P(k,q)/dE(k)dE(q)
and Strangeness Production on Stable
and Exotic Nuclei
40Ca
56Ca
• Antiprotons as a Probe for Nuclear Structure
• Antipoton-neutron Interactions in Neutron-rich Nuclei
• Antiproton Absorption in Neutron Skin Matter:
• 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
Antiproton Ion Collider (AIC) Collaboration @ FAIR
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