The Antiproton-Ion Collider

EC, 500 KV

NESR

R. Krücken

Technische Universität München

for the

Antiproton Ion ColliderCollaboration

The Antiproton-Ion Collider

EC, 500 KV

NESR

• Why another technique for nuclear radii?

• The Antiproton-Ion collider

• Simulations and rate estimates

• Summary and Outlook

rnp from antiprotonic atoms

Neutron-skin thickness in Sn isotopes

(1&2) RHB/NL3(3) RHB/NLSH

(4) HFB/SLy4(5) HFB/SkP

(p,p)

(3He,t)antiprotons

M. Bender, P.H. Heenen, P.G. ReinhardRev. Mod. Phys. 75 (2003) 122

Why the antiproton ion collider?

• charge radii can reliably measured (Lasers, (e,e’))

• several methods available for matter / neutron radii (p,p), (,’), (3He,t) reaction cross section, antiprotonic atoms

• results are • not always consitent• partly model dependent

• We need a method that determines proton and neutron radii

• using the same method

• in the same experiment

• at the same time

• independently

Antiproton Ion Collider (pbarA)

Rate estimate• 109 stored antiprotons

• Luminosity of 1023 cm-2 s-1 for 106 stored ions

• Typical total absorption cross-section: 1 barn

0.1 counts per second 1000 counts in 3 hours 0.01 fm stat. accuracy of rnp

Additional equipment:• 70kV electron cooler RESR• 70kV electron cooler pbar-ring• transfer line RESR – pbar-ring

• Antiprotons collected in RESR

• cooled and slowed to 30 MeV

• transferred to pbar-ring(Ring design by Novosibirsk group)

Limits due to T1/2 >1s and production yield (>104)

T1/2 =1s

Example: Z = 28-50

Theoretical cross-sections

Calculations by H.Lenske

theoryfrom Cwith

2

2

2

ppR

nnR

pntotalR

rC

rC

rC

200 MeV

400 MeV300 MeV

0

20

40

60

80

100

120

0 5 10 15 20

sig

AB

S(b

) [m

b]

Impact Parameter b [fm]

Antiproton-Nucleus Partial Absorption Cross Section 78Ni

50 MeV100 MeV

At lower energies one is moresensitive to the periphery of the density distribution ( energy scan)

Theoretical calculations – example 58Ni

Lenske, Wycech

A A-1

p

impact parameter b [fm]

z=4fm

z=-4fm

Pmiss(z): probability that pions miss the residual A-1 nucleus

Pdh: probability that residual nucleusis cold (E*< Sn,p)

About 30% of produced A-1 nuclei survive

Nuclear density

Simulations of the reaction kinematics

About 30% of produced A-1 nuclei survive

132Sn 131In132Sn 131Sn

z

-0.0

075

0.0

128

132Sn

Acceptancelimit of NESR

A A-1

p

q

p

q

p

qpz

z00

Measured momentum distribution is consistent with quasi-free scattering

F. Balestra et al., NPA491, 541 (1989)

LEAR data on Ne

Measured momentum distribution gives insight into angular momenta of annihilated nucleons

Schottky method for identification and counting of A-1 nuclei

von P. Kienle

Simulated momentum distributions

40Ca

40Ca 39K40Ca 39Ca

72Ni 71Co72Ni 71Ni

132Sn

132Sn 131In132Sn 131Sn

72Ni

A~130:A & both A-1 nuclei in the acceptance Schottky method using one ring setting recoil detection

A~70:A & and one A-1 nucleus in the acceptance Schottky method using zwo ring settings recoil detection

A<60:A-1 nucleus not in the acceptance recoil detection

A A-1

p

z

Recoil Detection after NESR dipole section

Existing ESR detector (TUM)

5 m

0.5

m

+7%

-6%

Staged set of recoil detectors covers large momentum range

Luminosity measurementusing elastically scattered antiprotons

Ions Antiprotons

Elastic scatteredAntiprotons

InteractionRegion

LuminosityDetector

to EC

from NESR

elast

elastdNLdt

lab [degrees]0 1 2 3 4 5 6D

iff.

Cro

ss-s

ect

ion [

b/s

r]

106

104

102

detector

AIC physics program

• benchmarking: radii for the Sn isotopic chain • stable isotopes, measured with different techniques• plan: extending from 105Sn to 135Sn

• radii along other closed-shell isotopic and isotonic chains

• radii for nuclei near the drip-line in light nuclei• transition from halo nuclei to neutron skins

• behaviour of radii across a shape transition• e.g. from 80Zr to 104Zr

• Odd-even effects in nuclear radii

• study the antiproton-neutron interaction

Summary and Outlook

• antiproton-nucleus cross section at 740 MeV/u is proportional to <r2>

• detection of A-1 products allows • determination of proton and neutron radii• in the same experiment (same systematic uncert.)• in a model independent way

• AIC is feasible in terms of technology and physics output

• Simple counting experiment using Schottky method or recoil detectors (once the collider runs)

• AIC allows systematic investigation of • Neutron skins• Transition from halos to skins• Odd-even staggering in radii• Shape coexistence and its effect on neutron and proton

radii• Nucleon-antiproton interaction

Antiproton-Ion Collider Collaboration

• Spokesperson / Deputy: R. KrückenC / J. ZmeskalA

• Project Manager / Deputy: P. KienleC / L. FabbiettiC

Beller, Peter A

Bosch, FritzA

Cargnelli, Michael B

Fabbietti, Laura C

Faestermann, Thomas C

Frankze, Bernhard A

Fuhrmann, Hermann B

Hayano, Ryugo S.D

Hirtl, AlbertB

Homolka, Josef C

Kienle, Paul B,C

Kozhuharov, Christophor A

Krücken, Reiner C

Lenske, Horst E

Litvinov, Yuri A

Marton, Johann B

Nolden, Fritz A

Ring, Peter C

Shatunov, Yuri F

Skrinsky, Alexander N. F

Suzuki Ken, C

Vostrikov, Vladimir A. F

Yamaguchi, Takayuki G

Widmann, Eberhard B

Wycech, Slawomir H

Zmeskal, Johann B

Institute A, Gesellschaft für Schwerionenforschung, Darmstadt, Germany (GSI)Institute B, Stephan Meyer Institut, Vienna, Austria (SMI)Institute C, Technische Universität München, Munich, Germany (TUM)Institute D, University of Tokyo, Tokyo, Japan (UoT)Institute E, Justus-Liebig Universität Giessen., Giessen, Germany (JLU)Institute F, Budker Institute of Nuclear Physics, Novosibirsk, Russia (BINP)Institute G University of Saytama, Saytama, Japan.(UoS)Institute H, Andrzej Soltan Institute for Nuclear Studies, Warsaw, Poland (IPJ)