Proton elastic scattering of 23,25F - ニュース · Proton elastic scattering of 23,25F Rui Jiu...

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


Outline

1 IntroductionThe structure in 25FMotivation

2 ExperimentSetupPosition reconstructionParticle Identification

3 ResultKinematics spectrum and excitation energy spectrumDifferential cross sectionOptical model

4 Summary


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]


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.


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.


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


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


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


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


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


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


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.


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.


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).]


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.


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).


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