Abdenbi KHOUAJA

Reaction cross section and strong absorption radius measurements of neutron-rich exotic nuclei

in the vicinity of closed shells N=20 and N=28

Reaction cross section and strong absorption radius measurements of neutron-rich exotic nuclei

in the vicinity of closed shells N=20 and N=28

I.N.F.NLaboratorio Nazionale del Sud

Catania

He3 He4 He6 He8

Li6 Li7 Li8 Li9 Li11

Be7 Be9 Be10 Be11 Be12 Be14

B8 B10 B11 B12 B13 B14 B15 B17 B19

C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C22

N12 N13 N14 N15 N16 N17 N18 N19 N20 N21 N22 N23

O13 O14 O15 O16 O17 O18 O19 O20 O21 O22 O23 O24

F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F29

Ne17 Ne18 Ne19 Ne20 Ne21 Ne22 Ne23 Ne24 Ne25 Ne26 Ne27 Ne28 Ne29 Ne30 Ne32

Na20 Na21 Na22 Na23 Na24 Na25 Na26 Na27 Na28 Na29 Na30 Na31 Na32 Na33 Na34 Na35

Mg21Mg20 Mg22Mg23Mg24Mg25Mg26Mg27Mg28Mg29Mg30Mg31Mg32Mg33Mg34Mg35Mg36

Ca35 Ca36 Ca37 Ca38 Ca39 Ca40 Ca41 Ca42 Ca43 Ca44 Ca45 Ca46 Ca47 Ca48 Ca49 Ca50 Ca51 Ca52

Al22 Al23 Al24 Al25 Al26 Al27 Al28 Al29 Al30 Al31 Al32 Al33 Al34 Al35 Al36 Al37 Al38 Al39

Si22 Si23 Si24 Si25 Si26 Si27 Si28 Si29 Si30 Si31 Si32 Si33 Si34 Si35 Si36 Si37 Si38 Si39 Si40 Si41 Si42

P26 P27 P28 P29 P30 P31 P32 P33 P34 P35 P36 P37 P38 P39 P40 P41 P42 P43 P44 P45 P46

S27 S28 S29 S30 S31 S32 S33 S34 S35 S36 S37 S38 S39 S40 S41 S42 S43 S44 S45 S46 S47

Cl31 Cl32 Cl33 Cl34 Cl35 Cl36 Cl37 Cl38 Cl39 Cl40 Cl41 Cl42 Cl43 Cl44 Cl45 Cl46 Cl47 Cl48 Cl49

Ar31 Ar32 Ar33 Ar34 Ar35 Ar36 Ar37 Ar38 Ar39 Ar40 Ar41 Ar42 Ar43 Ar44 Ar45 Ar46 Ar47 Ar48 Ar49 Ar50 Ar41

S48

K35 K36 K37 K38 K39 K40 K41 K42 K43 K44 K45 K46 K47 K48 K49 K50 K51 K52

Ca53

28

26

24

22

2018

16

1412

10

8642

A.C.C.Villari et al. en 1991

N.Aissaoui et al en 1999

Chulkov, Suzuki, Ozawa et al. en 2001

I.Licot et al en 1997

Reactio

n cross

sectio

n (σ R)

to be m

easured

Ne31

Goal of the experience

Y.H.Zhang et al. en 2002

Available data of the reaction cross-section

Primary beam

Secondary beam

Alpha Spectrom

eter

GA

NIL

Degrader

9Be with thickness of 25µm

48CaEnergy=60.3A MeV

Intensity=4000nAe

Production target181Ta

22C 21C23N

17B14Be11Li

29F

32Ne

35Na

38Mg

41Al

43Si

44P45S

47Cl

New

reac

tion

cros

s sec

tion

mea

sure

men

ts

Experiment Details

L. Bianchi et al., Nucl. Instr. and Meth. A276 (1989) 509.W. Mittig et al., Bormio, Italy 1986A. Gillibert et al., Phys. Lett. B176(1986)317.

M = Q B/L.Tvol

B= M V/Q

Long flight path = 82m Time of flight ~ 700ns - 1.2 sm/m ~ 10-4

SISSISISSI

Spectromètre Spectromètre AlphaAlpha

SPEG

NaI

NaI

beam

dE1dE2

EbarE

Silicon Telescope

SPEG-GANIL

NaI

NaI

Reaction cross-sectionDirect method developed by A.C.C.Villari

(which is a variant of the known transmission method)

In this method, the stack of Silicon detectors is used as both :

Reaction target

Detection system

max

max

0

max

0 1ln/

RNd

PA

dR

dEdEdRE

A

RR

E

R

R

Masse (MeV)~Etot.Tvol2

Typical mass spectra as a function of the total energy (~ET2) for 25F (E= 45.5A MeV). Energy resolution ~ 0.23%. Effective resolution Q=2.58MeV

Spectrum obtained directly from the silicon detectors

Spectrum in coincidence with emitted gammas

Spectra (a) :

Spectra (b) :

i

reaR N

NP

coinccorrcorr

reaNN

i

reaR N

NNP

reaction probability

Reaction probability PR

)1ln(

1(2

3/13/1

3/13/13/13/12

0

R

cm

b

tP

tPtPR

Pcste

E

VEC

AA

AAaAAr

Reduced strong absorption radius :

Parametrization of S.Kox

Results

More than 70 radii are measured

19 radii are measured for the first time:

27F, 27, 30Ne, 33Na, 28, 34-35Mg, 36-38Al, 38-40Si, 41-42P, 42-44S, 45Cl.

PAEEC /014.031.0

Parametrization of the reduced strong absorption radii:

Z≤13 : evolution according to :W.Mittig et al., Phys. Rev. Lett. 59, 1889 (1987)

Z≥13 : evolution according to:N.Aissaoui et al., Phys. Rev. C60, 034614 (1999)

1)(06.020 ZNr

30/3230/)(20 ZNr

8≤Z≤18 and 12≤A≤46 :

22

20

628.4282.0164.1 Tz

ATz

Ar

r02

TZ/A

stab

ilit

y

r02r0

2

New parametrization

A.Khouaja et al (ENAM04)

A.Khouaja et al (EXON04)

17F 23Al

27P

23O 29Ne

22N

24F

Strong influence of the isospin is revealed for each isobar, New parametrization permits : To study the evolution of the matter distribution : efficiently reproduces the skin effect To give a fast indication on the existence of abnormal structures: deformation, halo… for these nuclei: 23N, 29Ne, 33Na, 35Mg, 44S, 45Cl, and 45Ar

35Mg

44S

41Ar

33Na

45Ar45Cl

Glauber Model

The effective nuclear matter radii “RMS”

The effective density distributions

permits us to deduce:

Coulomb-modified Glauber Model:

0

)(1)1(2 bdbbE

V

cm

CR

)()()()( 212122

12 bbbbbfbdbdb P

zCz

)()( 22

,, zbdzb CPCP

z

CP

pnCPnpCPnnCPppCPNNtot AA

NZZNNNZZ

))(exp()( bbT NNtot

Thickness density :

:

Transparency function :

)2

exp(4

1)(

2

2

2NNNN

bbf

089.0)679.106

exp(996.0 E

NN

Profile function :

T. ZHENG et al., Nucl. Phys. A709, 103 (2002)R.M. Devries et al., Phys. Rev. C22, 1055 (1980)

Standard Glauber model

Coulomb-modified Glauber model

1

22,

22,

2

32,

0, 14

3

pFk

pFk

pFkk R

a

R

k

pFk

pFk

kpFk

a

Rrr

2,

2,

0,2,

exp1)(

)( 3/13/122, NorZrR pFpFk

22,

22,

22

2,2

3

71

5

3

pFn

pFnpFnn R

aRr

22,

22,

22

2,2

3

71

5

3

pFp

pFppFpp R

aRr

npm rANrAZr 222 )/()/(

2/122/12pn rrR

Matter radii: Radius Mean Square

Matter distribution: using 2pF density distribution

Skin effect

where: k=Z or N

Two free parameters

fmNaRNaR pFnA

pFp 114.3)()( 232,2,

fmNaaNaa ApFp

ApFn 401.0)()( 2,2,

.

3/12, ZrR ppFp pa

Absence of data at intermediate energy:

T.Suzuki et al.,

Phys. Rev. Lett. 75, 3244 (1995)

Presence of data at intermediate energy :

We disentangle: 3/12, NrR npFn and,

The results of T.Suzuki (Phys. Rev. Lett. 75, 3244 (1995))

Actual work

na,

Prel

imin

ary

resu

lts

protons

neutrons

Si-target

C-target

Matter density distributions

Matter Radii Mean Square

L.S. Geng et al, Nucl. Phys. A 730(2004)80

Conclusion

In the same setup, more than 70 reaction cross sections are measured The measurements , for the first time, of 19 new reaction cross sections

New phenomenological parametrization is suggested for the nuclear radii in the region of closed shells N=8 and N=28, which permits :

to reproduce the skin effect far from stability to give a current indications on the existence of abnormal structure: 23N, 29Ne, 33Na,

35Mg, 44S, 45Cl, and 45Ar

We disentangle the effect of nuclear size and surface diffusivity of matter distribution using Glauber model.

Great thanks to MAGNEX’s group:A.Cunsolo, F.Cappuzzelo, J.S.Winfield,

C.Nocifiro, A.Khouaja, A.Foti, S.E.A.Orrigo, M.Cavallaro

Collaborators:D.Hirata Open University, U.KA.C.C.Villari GANIL, Caen, FranceM.Benjelloun LPTN, El jadida, MoroccoA.Khouaja LNS-INFN, Catania, Italy

Participants:H.SAVAJOLS1, W.MITTIG1, P.ROUSSEL-CHOMAZ1, N.ORR2, S. PITAE1, C.E.DEMONCHY1, L.GIOT1,

M.CHARTIER3, A.GILLIBERT4, D. BAIBORODIN5, Y. PENIONZHKEVICH6, W.CATFORD7, A.LÉPINE-SZILY8, Z.DLOUHY6

1GANIL (IN2P3/CNRS – DSM/CEA), B.P. 55027 14076 Caen Cedex 5 France2LPC, ISMRA et Université de Caen, F-6704 Caen, France

3University of Liverpool, Dept. of Physics, Liverpool, L69 7ZE, UK4SPHN (DAPNIA/CEA), CEN Saclay, F-91191 Gif-sur Yvette, France

5FLNR, JINR, Dubna, P.O.Box 79, 101000 Moscow, Russia6Nucl.Phys.Ins., ASCR, 25068 Rez, Czech Republic

7University of Surrey, Stoy Fill, Nuclear Physics Dept, Guilford, GU27XH, UK8University of São-Paulo, IFUSP, C.P.66318, 05315-970 São –Paulo, Brazil

MERCI DE VOTRE ATTENTION

)2

exp(4

1)(

2

2

2NNNN

bibf

)2

exp(4

1)(

2

2

2NNNN

bbf

089.0)679.106

exp(996.0 E

NN

42

2

67.68/76.8/04.1573.13

85.113/26.25/18.1867.70

nnpp

np

cv /

NNtot

avec

)()()(exp12)( 212122

12 bbbbbfbdbddbbb P

zCz

NNtotR

)()(exp12)( 1112 bbbbddbbb P

zCz

NNtotR

finite range

zero range

R.M. Devries et al., Phys. Rev. C22, 1055 (1980)

T. ZHENG et al., Nucl. Phys. A709, 103 (2002)

S.K Charagi et al., Phys. Rev. C41, 1610 (1990)

profile function :

Discovery of a new magic number, N=16 :

A.Ozawa et al., Phys. Rev. Lett. 84, 5493(2000)

Possible existence of one-neutron halo structure : 22N, 23O, 24F

Appearance of a new magic number N=16

Magic number

Matter distribution far from stability Halo structure

Skin structure

RMF: 1n-halo nuclei: 33Na, 34Na and 35Mg

T.Suzuki et al, Nucl. Phys. A616, 286c (1997)

J.S.Wang et al., Nucl. Phys. A691, 618(2001)

17B14Be

11Be

11Li

8He

6He

I.Tanihata et al, Phys.Lett. B206, 592 (1988)

Our results are slightly small to the results of T.SuzukiThe precision of different results are amelioratedAs a preliminary results, the skin effect is revealed in the structure of these nuclei

2.79 0.132.63 0.030.262.740. 042.480.043.332.970.24724Ne

2.82 0.042.74 0.030.272.850.042.580.043.222.810.37025Ne

2.86 0.052.82 0.020.262.920.032.660.023.022.590.4726Ne

2.96 0.052.83 0.040.302.950. 052.650.053.583.160.27027Na

3.04 0.032.93 0.020.323.050.032.740.033.483.010.38528Na

3.06 0.062.98 0.020.333.100.032.770.033.402.880.44029Na

3.01 0.102.91 0.050.253.010. 062.770. 063.383.010.40029Mg

3.08 0.082.99 0.020.293.100.032.810.033.473.030.41530Mg

3.12 0.133.04 0.030.363.180. 052.810.043.703.170.37031Mg

Rn, 2pFRp, 2pFa2pFNoyaux 2/12

nr R 2/12mr T.Suzuki2/12

pr