National Institute of Radiological Science (NIRS)
S. Suzuki, A. Kitagawa, M. Fukuda, S. Sato
Reaction cross sections of 14B and 8Heon proton target for the separation
of proton and neutron density distributions
M. Tanaka, Osaka Univ., Japan
Osaka Univ.M. Fukuda, K. Matsuta, M. Mihara,
Y. Morita, Y. Kamisho, J. Oono,R. Kanbe, S. Yamaoka, K. Watanabe Tokyo Univ. Sci.
D. Nisimura, S. Kinno, Y. Taguchi
Niigata Univ.M. Takechi, T. Ohtsubo, T. Izumikawa,
A. Honma, D. Murooka
Saitama Univ.T. Suzuki, T. Yamaguchi, J. Kouno,
S. Yamaki, S. Matsunaga
σpn > σpp(nn)
Nucleon-nucleon total cross section σNN ( * )
σR on proton target
p-n asymmetry
Proton target(Largest p-n asymmetry)
σNN has high sensitivity to the surface structure of nucleus
at Intermediate energy region.
* (http://pdg.lbl.gov/2010/hadronic-xsections/hadron.html)
Sensitive to the composition of surface
〜 3 timesProtonProton
NeutronProton1s1/2
1p3/2
1p1/2
2s1/2
1d5/2
NeutronProton1s1/2
1p3/2
1p1/2
2s1/2
1d5/2
Neutron rich nucleus 14B
14B
Magnetic moment [1]
Q moment [2]
1n removal reaction [3,4]
(14B→13B+n)
These data point out large contribution of 2s1/2 orbit.
[1] H. Okuno et al., Phys. Lett. B354, 41 (1995).[2] H. Izumi et al., Phys. Lett. B366, 51 (1996).[3] D. Bazin et al., Phys. Rev. C57, 2156 (1998).[4] V. Guimaraes et al., Phys. Rev. C61, 064609 (2000). [5] G. Audi and A. H. Wapstra, Nucl. Phys. A 565 (1993).
S1n= 0.970(21)MeV [5]
so small
Halo nucleus
Neutron rich nucleus 8He
[*] ] I. Tanihata, et al., Phys. Lett. B 160 (1985) 380-384. [**] A.A. Korsheninnikov, et al.,Nuclear Phys. A 617 (1997) 45-56.
Structure ?
σI at high energy [*](790MeV/nucleon)Elastic Scattering [**]
Large neutron radius
Nucleon density distribution of 8He
[**]
Purpose of this study
Measurement of the σR for 8He and 14B ① on nucleus targets
② on proton targets at intermediate energies
Obtaining the information of proton and neutron density distributions respectively
from σR on nucleus and proton targets.
Set upHIMAC in Chiba (Japan)
SB2 Course14B 130, 110, 85, 60MeV/nucleonPrimary beam 18O, 15N 160AMeVF0 Target Be 3.0, 0.55g/cm2
8He 125, 110, 80, 65MeV/nucleonPrimary beam 11B 160AMeVF0 Target Be 3.7, 9.2g/cm2
Production Target(F0)
BeamDegrader
Slit
D1
D2
F1PL
Slit
Go to F3 focal plane
ΔECsI(Tl)F1PL F3PL
TOFΔE
Reaction Target
VETOSi NaI(Tl)
PPAC
E
Bρ − TOF − ΔEΔE − E
At F3 Focal Plane
Upstream
Measurement of σR
Transmission methodReaction target: Be, C, Al, CH2
Proton=(CH2 − C)/2
Glauber calculation
Nucleon-Nucleon total cross section ( * )
Density distributionof projectile nucleus.
(Model density)
Density distributionof target nucleus
* (http://pdg.lbl.gov/2010/hadronic-xsections/hadron.html)
Nucleon-nucleon total cross section σNN ( * )
withModified Optical Limit approximation.
ρN of 14B, 8He Nucleus target
ρn, ρp of 14B, 8HeProton target
Obtain this information
Derivation of proton and neutron density distributions ρp, ρn
χ2 fitting with the width of ρp as a free parameter.
ρNucleon
ρn is deduced by subtraction.ρn=ρN− ρp
From σR on nucleus target
ρp and ρn of 8He ρp(R) and ρN(R)
σR(E) on proton target
σI @ LBL [*]
σR(E) on nucleus target
[*] I. Tanihata, et al., Phys. Lett. B 160 (1985) 380-384
ρp and ρn of 14B ρp(R) and ρN(R)
σR(E) on proton target Neutron tail
σR(E) on nucleus target
σI @ LBL [*]
[*] I. Tanihata, et al., Phys. Lett. B 206 (1988) 592-596
8He root mean square radii Rproton, Rneutron, Rmatter
[1] I. Tanihata et al., Phys. Lett. B 289, (1992) 261-266.[2] G. D. Alkhazov et al., Nucl. Phys. A. 712, (2002) 269-299[3] M. Puchalski et al., Hyperfine Interact (2010) 196:35-42[4] R. Baldik et al., Phys. of Atomic Nuclei (2010) Vol. 73, No. 1 74-80
14B root mean square radii Rproton, Rneutron, Rmatter
[2] A. Bhagwat et al., Eur. Phys. J. A. 8, 511-520 (2000)[3] H. Takemoto et al. Phys. Rev. C. 63. 034615
Preliminary
Summary• We measured σR for 8He and 14B on nucleus and proton targets at
the HIMAC heavy ion synchrotron facility.
• ρp and ρn were separated successfully through the χ2 fitting procedure with the modified Glauber calculation.
• Rp, Rn, Rmatter were derived from ρp, ρn and ρN.
• As a future prospect, we will finalize the data analysis. And we deduce more accurate ρp, ρn of 8He and 14B, then make a detailed discussion on their structures.
Sub
Energy dependence of σR
on Nucleus target
Nucleon density distribution ρN
Relation between Reaction cross section(σR)and density distribution
It is impossible to clarify a composition of the surface
by means of σR
on p-n symmetric target.
σR
High energy →The inner part of nucleusLow energy →The outer part of nucleus
p-n symmetric target
Measurement of σR
〜Transmission method〜
Incident partices
Reaction target
Detector1
Detector 2
Incident particles
Non-reacted particles
N1in N2
in
Reation target outDetector 1 Detector 2
Non-reacted particles
N1out N2
out
Target thickness t
Correction for reactions in the detector.
ρN of 8He
Best FitCore: Z=2, N=4Tail: 2nucleons (1p3/2 orbit)
The core is not a “bare” 6He.(6He is a halo nucleus.)
S2n=2.14MeV
Best Fit is 1p3/2 2nucleon with B.E= 3MeV
Single particle density calculation
Binding Energy
Woods-SaxonCoulombCentrifugal Potential
Calculate SP density with adjustingthe potential depth to reproduce
Binding energy.
Best Fit Results14B 2s1/2 orbit with B.E=0.97MeV(consistent with S1n=0.97MeV)
8He 1p3/2 orbit with B.E=3MeV(inconsistent with S1n=3MeV)
TailNeutron or Proton
Orbit2s1/2 or 1d5/2
TailNeutron or Proton
Orbit2s1/2 or 1d5/2
14B Comparison between Exp. and Calc. value
σR for 8He on nucleus targets
[*] I. Tanihata, et al., Phys. Lett. B 160 (1985) 380-384.
σI @ LBL(Tanihata et al.)
Preliminary
σR for 8He on proton targets
σRH=(σI
CH2−σIC)/2
σR on proton target
Measurement of interaction cross section σI
on C, CH2 targets.
Determined by subtracting the σI
C from σICH2.
CH2 : Polyethylene
σI for 14B, 8He on C, CH2 targets.