Upload
duongduong
View
228
Download
8
Embed Size (px)
Citation preview
Proton elastic scattering of 23,25F
Rui Jiu Chen1,2
Email: [email protected]
1School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University,Beijing 100871, China
2RIKEN Nishina Center, Hirosawa 2-1, Wako, Saitama 351-0198, Japan
FB20 conference, 2012parallel IV-d
RuiJiu Chen (Peking University) FB20 FB20 2012 1 / 17
Collaborators
RIKEN,Nishina center,Japan:H. Otsu, H. Baba, N. Fukuda, N. Inabe, D. Kameda, M. Matsushita, T.Motobayashi, E.Y. Nikolskii, M.K. Nishimura, T. Onishi, H. Sakurai, M. Takechi, S.Takeuchi, Y. Togano, K. Yoneda, A. Yoshida, K. Yoshida
CEA-Saclay, DSM/IRFU SPhN, F-91191 Gif sur Yvette Cedex, France:V. Lapoux, S. Boissinot, E. Pollacco, F. Flavigny, C. Louchart, L. Nalpas, A.Obertelli
Institut de Physique Nucle aire, IN2P3-CNRS, F-91406 Orsay, France:A. Matta, Y. Blumenfeld, S. Franchoo, F. Hammache, E. Rindel, P. Rosier
GANIL, CEA/DSM - CNRS/IN2P3, BP 55027, F-14076 Caen Cedex5, France:P. Gangnant, C. Houarner, J.F. Libin, F. Saillant
RuiJiu Chen (Peking University) FB20 FB20 2012 2 / 17
Outline
1 IntroductionThe structure in 25FMotivation
2 ExperimentSetupPosition reconstructionParticle Identification
3 ResultKinematics spectrum and excitation energy spectrumDifferential cross sectionOptical model
4 Summary
RuiJiu Chen (Peking University) FB20 FB20 2012 3 / 17
Introduction The structure in 25F
The structure in 25F
25F is important for the study of nuclear structure
One proton off doubly magic nucleus 24O [K. Tshoo et al.,PRL109(2012)022501]
Magic number 16 [A. Ozawa et al., PRL84(2000)24]
RuiJiu Chen (Peking University) FB20 FB20 2012 4 / 17
Introduction The structure in 25F
The structure in 25F
Previous studies on 25F
The sudden change of drip line: O-> F[H. Sakurai et al., PLB448(1999)180]
22C, 23N, 24O, 29F
Large interaction cross section [A. Ozawa et al., NPA691(2000)599]
Narrow fragment momentum distribution [E. Sauvan et al.,PRC69(2004)044603]
The nonlinear relativistic mean-field (RMF) theory: Zhongzhou Ren et al.,J. Phys. G: Nucl. Part. Phys. 22, 523-526.1-neutron halo in 24F, 3-neutron halo in 26F
The valance proton expects to play importance role in the structure of 25F.
RuiJiu Chen (Peking University) FB20 FB20 2012 5 / 17
Introduction Motivation
How the valance proton works on the 25F system?
Elastic scattering:
Provide the surface propertiesDetect the density distributionObtain the optical potentialExpected to provide more detailed information.
Questions:
Whether there is a change in the structure of 25F?Study the structure of 23F and 25F by elastic scattering.
RuiJiu Chen (Peking University) FB20 FB20 2012 6 / 17
Experiment Setup
BigRIPS, MUST2 detector array, and ZDS
Primary beam: 48Ca, 345 MeV / A, 3 g/cm2 Be, ∼100 particle nASecondary beam:
23F, 9.6 × 103 (purity 23%) cps , 289 MeV / nucleon25F, 330 (purity 1.3%) cps, at 298 MeV / nucleon
BigRIPS: F0-F7, ∆E-Bρ-TOFZDS: F7-F11, ∆E-Bρ-TOF
RuiJiu Chen (Peking University) FB20 FB20 2012 7 / 17
Experiment Setup
MUST2 telescopes at F8
Placement: 23 cm surrounding thetarget
Configuration: 300 µm DSSD +4 cm thick, 16 fold CsI detector
Active area: 10 × 10cm2
Position resolution of MUST2:∼ 0.8 mm/strip
Energy resolution of DSSD:∼ 94keV (FWHM) for ∼ 5.5 MeV α ray
Angular region:30 ∼ 90 in the laboratory frame
RuiJiu Chen (Peking University) FB20 FB20 2012 8 / 17
Experiment Position reconstruction
Track of incident beam
PPACType:
F8PPAC1,2 is doublelayer delayed linePPACF8PPAC3 is singlelayer delayed linePPAC
Number:3 set of PPAC5 layers for x and yrespectively
Efficiency of single layer for F isotopes :∼ 70 % for F8PPAC1,2 and 50% for F8PPAC3Efficiency of track: 95%
Position resolution of profile on target: ∼3.8 mm in FWHMAngular resolution of proton: ∼10 mrad in FWHMSecondary target: 2.7 mg/cm2 CH2 and 0.78 mg/cm2 C ,rotated by 45
RuiJiu Chen (Peking University) FB20 FB20 2012 9 / 17
Experiment Particle Identification
PID of beam:BigRIPS and ZDS
23F beamEnergy: 289MeV/AIntensity: 9.6 ×103 cpsPurity: 23%
25F beamEnergy: 298MeV/AIntensity: 330cpsPurity: 1.3%
Sat Aug 11 20:30:30 2012A/Z
2.4 2.6 2.8 3 3.2Z
6
7
8
9
10
11
1
10
210
310
F23
BigRIPS
Sat Aug 11 20:30:30 2012A/Z
2.4 2.6 2.8 3 3.2
Z
6
7
8
9
10
11
1
10
210
F23 ZDS
Sat Aug 11 20:30:30 2012A/Z
2.4 2.6 2.8 3 3.2
Z
6
7
8
9
10
11
-110
1
10
F25
BigRIPS
Sat Aug 11 20:30:31 2012A/Z
2.4 2.6 2.8 3 3.2Z
6
7
8
9
10
11
1
10
210
F25
ZDS
RuiJiu Chen (Peking University) FB20 FB20 2012 10 / 17
Experiment Particle Identification
PID of scattering particle
Mon Aug 20 11:59:51 2012[MeV]CsIE
0 50 100 150
[MeV
]D
SSD
dE
0
1
2
3
4
5
6
7
8
9
10
-110
1
10
> 6.2 MeV, dE ~ EpE
Mon Aug 20 11:59:51 2012[MeV]DSSDE
0 2 4 6 8 10
[ns]
DSS
DTO
F
130
135
140
145
150
155
160
165
170
1
10
210
p
dt
< 6.2 MeV, E ~ TOFpE
Scattering particles penertrate the DSSD (∼300 µm)Ep >6.2 MeV, dE-E
Scattering particles stopped inside DSSDEp <6.2 MeV, E-TOF
RuiJiu Chen (Peking University) FB20 FB20 2012 11 / 17
Result Kinematics spectrum and excitation energy spectrum
The kinematics spectrum and excitation energy spectrum of 23F and 25F
Correction:Position shift of MUST2and PPACEnergy loss insidetarget, dead layer ofDSSD, and dead layerof CsI
Select conditions:Beam@BigRIPS && Target &&Proton@MUST2 &&Beam@ZDS
Ground state
σ(Ex) ∼ 0.8 MeV
Fri Aug 17 23:40:20 2012[Deg]labθ
70 75 80 85
E[M
eV]
0
10
20
30
40
50
60
70
-110
1
10
F + p23
Fri Aug 17 23:40:20 2012E[MeV]
-10 -5 0 5 10
[Cou
nts/
500k
eV]
0
20
40
60
80
100
120
140
160
180=0.87 MeVσ
F + p23
Fri Aug 17 23:40:20 2012[Deg]labθ
70 75 80 85
E[M
eV]
0
10
20
30
40
50
60
70
-110
1
10
F + p25
Fri Aug 17 23:40:20 2012E[MeV]
-10 -5 0 5 10
[Cou
nts/
500k
eV]
0
10
20
30
40
50
60
70
80=0.81 MeVσF + p25
RuiJiu Chen (Peking University) FB20 FB20 2012 12 / 17
Result Differential cross section
The differential cross section of 23F and 25F
(Deg)c.mθ
0 5 10 15 20 25 30
(mb
/sr)
cm
Ω /
dσ
d
110
1
10
210
310
F(p,p)23
F(p,p)25
Carbon componentTo be structureless(carborn target measurement)
Inelastic scattering: estimated to be negligible( dσdΩ
)25F <
( dσdΩ
)23F at forward angle.
RuiJiu Chen (Peking University) FB20 FB20 2012 13 / 17
Result Optical model
The calculation with KD potential
Solid line:KD potential parameters.[A.J.Koning,J.P.Delaroche,Nucl. Phys. A713, 231(2003).]
(Deg)c.mθ
0 5 10 15 20 25 30
(mb
/sr)
cm
Ω /
dσ
d110
1
10
210
310
F23(p,p). 5/2+ KD
F23(p,p).
(Deg)c.mθ
0 5 10 15 20 25 30
(mb
/sr)
cm
Ω /
dσ
d
110
1
10
210
310
F25(p,p). 5/2+ KD
F25(p,p).
KD potential parameters:
( dσdΩ
)23F reasonably agrees with the calculation with KD potential,( dσ
dΩ
)25F is smaller than the calculation with KD potential.
RuiJiu Chen (Peking University) FB20 FB20 2012 14 / 17
Result Optical model
Fit the cross section of 25F by changing different parameters
No unique parameters without assumption
Fix the real, surface and spin orbital part ofpotentail.
Set. 1, Fix the shape of imaginary(aIand rI ), change the depth ofimaginary part (I).Set. 2, Change both the shape anddepth of imaginary(I, aI and rI ).
(Deg)c.mθ
0 5 10 15 20 25 30
(mb
/sr)
cmΩ
/ d
σd
110
1
10
210
310
F25(p,p).
KD
,Change II
and rI
Set. 1: Fix a
I, rI
Set. 2: Change I, a
One possible and more intuitive model: Eikonal approximation.[S. Hirenzaki et al., Nucl. Phys. A552, 57 (1993).]
RuiJiu Chen (Peking University) FB20 FB20 2012 15 / 17
Summary
Summary
Experiment23,25F (p,p) have been measured for the first time at Elab = 289 and 298 MeV nucleon,respectively, using the MUST2 silicon strip detector array.
Differential cross section
p + 23F and p + 25F.Cross section of 25F < 23F.
Optical model calculation
Reproducing the experimental data of 23F with KD potential parametersReproducing the cross section of 25F by changing imaginary part of the KDpotential parameters.
Summary:The potential with a shallow and long tail imaginary part can reproduce the data well.
RuiJiu Chen (Peking University) FB20 FB20 2012 16 / 17
Summary
K. Tshoo et al., Phys. Rev. Lett. 109, 022501 (2012).
A. Ozawa et al., Phys. Rev. Lett. 84, 24 (2000).
H.Sakurai et al., Phys. Lett. B 448, 180 (1999).
A.Ozawa et al., Nucl. Phys. A 691, 599 (2001).
E. Sauvan et a, Phys. Rev. C 69, 044603 (2004).
Zhongzhou Ren., J. Phys. G: Nucl. Part. Phys. 22, 523-526 (1996).
S. Hirenzaki et al., Nucl. Phys. A552, 57 (1993).
RuiJiu Chen (Peking University) FB20 FB20 2012 16 / 17