Chen Jie，Lou Jian-Ling, Ye Yan-Lin
Peking University, China
August 17, 2012
The halo nucleus
 Neutron loosely bound
11Be
Sn=0.504 MeV
 Larger radius
rms= 2.91 fm
 Parity inversion： intruder state

10Be
core + 1 valance n
10Be
Core excited to 2+
PRC 85 (2012) 051303R
0 d3/2
1 s1/2
⑳
11Be (1/2+
gs
)
0 d5/2
inversion
⑧
0 p1/2
0 p3/2
0 p1/2
1 s1/2
0 d5/2
0 p1/2
2+
0 s1/2
0+ × 1s1/2
PRL 108, 192701 (2012),10Be(d,p)
S~0.71(5)
2+ × 0d5/2
PLB 461, 22-27 (1999) 11Be(p,d)
S~16%
PRL 84, 35(2000) 11Be 1n removal
Reaction， momentum distribution S~22%
12Be = 11Be + n
Intruder state
[6]F. C. Barker, J. Phys. G 2, L45 (1976).
Normal state
12Be
• disappearance of conventional magic number： N=8
• Isomeric state： 02+ 331(12) ns
Two decay modes:
E2 decay: 130 keV and 2.11 MeV gamma-rays
E0 decay: internal conversion: negligible
e+e- pair creation 511keV gamma
17(2)%
isomer
83(2)%
Physics Letters B 560 (2003) 31–36;
Physics Letters B 654 (2007) 87-91.
0 d3/2
1 s1/2
0 d5/2
⑳
12Be (0+
gs
)
⑧
0 p1/2
0 p3/2
0 s1/2
Normal
0 p1/2
(0s)4(0p)8 0ћω
1 s1/2
0 d5/2
Intruder state (0s)4(0p)6(1s0d)2 2ћω
01+ G.S
02+ Isomer
Inutruder
normal
intruder
norm
al
reference
No data: no data or no calculation
Not: Intruder state is not dominant
Dominant: Intruder state is dominant
Uncertainty: no d-wave, could not make sure
d
p
F.C.Barke
33
34
32
56
2
42 Dominant dominant J.Phys.G 36,038001,2009;
J.Phys.G 2, L45,1976
H.T.Fortune and
R.Sherr
53
15
32
25
7
68 dominant
Not
Phys.Rev.C 74,024301,2006; J.Phys.G
038002,2009;
Phys.Rev.C83,044313,2011.
C.Romero-Redondo
Three –body model
?
10- 13-19 1513
23
68
?
Not
Phys.Rev.C 77,054313,2008.
G.Blanchon pp-RPA
25
18.5
0
19 Not
M.Dufour
74
p
Isomer
s
58
s d
G.S
dominant
dominant Phys.Rev.C 82,034313,2010.
NCSM
16
59
no
Not
No data
Nucl.Phys.A 836,242,2010.
Knock -out reaction
68
32
no
dominant
No data
Phys.Rev.Lett 85,266,2000;
Phys.Rev.Lett 96,032502,2006.
no
60 dominant
Not
Phys.Rev.lett 108,122501,2012.
Charge exchange
reaction
no
no
25
no
Transfer reaction
0.28
no
no
0.73 no
no uncertainty dominant
~0.20
no
no
0.32- no
0.95
no uncertainty uncertainty Phys.Rev.C 88,044619,2013
Phys.lett.B 682,391,2010.
Ground state：transfer reaction could not give the clear result, are no conflict with others
Isomeric state：transfer reaction contradict with Charge-exchange
Knock-out experiment(2ћω)
 78 MeV/u
12Be+9Be(s
wave)
Phys.Rev.Lett 85,266,2000.
don’t distinguish (1s1/2)2 and (0p1/2)2 configurations ------gamma rays
not sensitive to the (0d5/2)2 configuration--------10Be+n fragments
 39 MeV/u
12Be+12C(s
p d wave)
Phys.Rev.Lett 96,032502,2006.
4 NaI detectors: detect the first excited state of 11Be at 320keV(0p1/2)
Demon: detect n, n+10Be reconstruct the excited state of 11Be at 1.78
MeV(0d5/2)
Discriminate isomeric states from ground state
12B(1+)(7Li, 7Be)12Be(
2ћω) Phys.Rev.Lett 108,122501,2012.
 Gamow-Teller transition
Selected rules: Δ L=0, Δ S=1 , Select p-wave（normal）.
 Clearly distinguish the first two 0+ states of 12Be.
01+ 25（5)% 02+ 60(5)% --intruder states are dominant
for ground state(01+), but not for isomeric state( 02+)
11Be(d,p)12Be
reaction(0ћω) Phys.Lett.B 682,391,2010.
 Two annular DSSD
Phys Rev C 88,044619,2013
 Select s-wave（abnormal）
 Identify the excited states of 12Be
01+ 0.28 ,
02+ 0.73 Intruder state dominate
Phys.Rev.C 85,051303(R),2012.
1. 01+ ：normalization,
unsure deuterium content
2. 02+ : Mix with 2+ state.
separate them incorrectly
Normalization factor for beam.
Incident energy is about 2.8 MeV/nucleon
Target thickness: 1.0 mg/cm^2
No 0-degree detectors due to higher beam intensity
Thick target and Gamma detectors to discriminate the excited states of 12Be.
01+， SF = 0.15~0.25；
02+ ， SF = 0.32-0.98.
(1) For 01+:
no coincidence with 12Be
Larger background
(2)For 02+
Larger C.M angles
(3)target :H Percent(larger)
(4) No elastic scattering data
For 11Be+d and 12Be+p
G.S SF = 0.15 ~ 0.25
Isomeric： SF = 0.32 ~ 0.95 .
OPs of entrance channel (11Be+d) and exit channel (12Be+p) affect SF extraction largl
Goal of the proposed experiment
 Main goal:
Investigate the intruder s-wave strength in the ground state and
low-lying excited state of 12Be via the d(11Be,p) transfer reaction
at 20-30 MeV/u.
 20-30 MeV/u : to get the highest beam intensity
1. SF is independent of the incident energy in large energy range
2. reduce the effect of complicated reaction mechanism
3. beam production rate times reaction cross sections
4. 55MeV/nucleon 12Be+p elastic scattering data exist
The New ideas
 Decrease the background
Coincident measurement of 10-12Be and light-charged particles
 remove the effect of proton in CD2 target
Compare the elastic scattering data of 11Be+p to 11Be+d to get the
proton content in CD2 target.
 New technique to separate 02+, measure Smaller angles data
implantation-decay-detect gamma( stopping and decay)
 Measure the elastic scattering Channel at the same experiment
Kinematics
Experimental Setup
NaI
Tele1
Annular DSSD
Tele0
Tele2
Beam
 Beam :






Primary beam: 13C
Energy:
57.7 MeV/u
Intensity at F3: 1.5*10^4pps
Purity:
90%--93%
Contamination: mainly 9Li
Energy dispersion: 2%
Intensity:
800 enA
Secondary beam : 11Be
On zero Tele: 2.0*10^4pps
Energy: 27 MeV/nucleon
Beam time:
10 days
Beam
11Be
10Be
9Li
8Li
11Be
9Li
Elastic scattering Data of 11Be+p
and 11Be + d
Extract Optical potential for the
Entrance channel of transfer reaction
11Be
elastic and inelastic scattering on proton
PID on the
zero degree
telescope
Energy spectrum for 11Be
cut 10Be on Tele0
cut 11Be on Tele0
Kinematic loci for
protons in coincidence
with 11Be on Tele0
Solid angle---Geant4 simulation
1
60
0.1
0.01
0.001
0.0001
65
70
75
80
85
90
ADWA method：
Provide the OP
Of entrance channe
Systematic is good.
Need normalization
Factor
Provide by D.Y.Pang and J.Chen
[1] 38.3 MeV/nucleon PLB 2008, 658: 198-202
[2] 49.3 MeV/nucleon PLB 1997, 401: 9-14
[3] 63.7 Mev/nucleon PLB 2004,596: 54-60
with core
excitation
Without core
excitation
Provide by A.M.Moro
DCE: dynamic core excitation
G0: OP-N Gaussian potential fitting deuteron 3s1 phase-shifts
BX: deformed n+10Be (particle-rotor model of Nunes et al)
CDCC: Continuum discreted coupled channel
XCDCC: Extended CDCC
11Be
elastic and inelastic scattering on deuteron
Energy in DSSD / artificial unit
PID on the zero degree telescope
energy spectrum for 11Be
cut 11Be on Tele0
11Be
cut 10Be on Tele0
10Be
Energy in SSD/MeV
Energy/MeV
Provide by D.Y.Pang and J.Chen
Global JLM potential can reproduce
the Angular distribution of 11Be+d
DWBA: provide 11Be+d OP
[1] PRC 83, 064619 (2011)
[2] JPG 39 (2012) 095101
Provide by A.M.Moro
Need more discussion
Angle of deuteron(degree)
Energy of deuteron(MeV)
Angle of 11Be(degree)
nergy of deuteron(MeV)
Counts
H in CD2 target (9.5%)
Angle of Deuteron(degree)
OP of the exit channel
We need 51 MeV/nucleon data
100
Experimental data at 55 MeV/nucleon
CH89 V = 0.70
d/dR
80
Curve 1
60
40
20
0
0
10
20
30
40
50
c.m(degree)
Curve 1: Optical model fitting
Curve 2: 12C+p OP
Physics Letters B 343 (1995) 53-58;
Using CH89 systematic OP to refit the
Angular distributions to get the exit channel OP
Transfer reaction
Counts/500 keV
Proton coincident with 12Be
Isomeric mixed with 2+ and 1Mean=-2.14MeV
Sigma=0.65Me
Mean=0.22MeV
Sigma=0.5MeV
G.S
12Be
Energy(MeV)
Q-value
Angle(degree)
Experimental Setup
NaI
Tele1
Annular DSSD
Tele0
Tele2
Beam
NaI(Tl) + PMT
High-voltage affects gain
Gain varies with time
Peak channel
Peak channel varies with time
2340
2330
2320
2310
2300
2290
2280
2270
2260
Open chamber
Open chamber
80
130
180
Time(File number)
230
280
Counts/10keV
Counts/30keV
Before
Resolution become better
after
11Be beta-decay
Isomeric state(E0 decay was used)
E0: 83%
511 keV
e+e- pair
creation
T1/2 = 331 ns
E2: 17%
130 keV and 2100 keV
S. Shimoura et al., Physics Letters B 560 (2003) 31–36;
S. Shimoura et al., Physics Letters B 654 (2007) 87-91.
Counts/ 30 keV
Gamma+ proton + 12Be
Mean= 528keV
Sigma= 24.8keV
Energy(keV)
Half-life of isomeric state
Counts/100ns
Proton（around 2MeV in Q_value）+ 511keV gamma
T ½ = 331 (12) ns
PLB 560 (2003) 31–36;
PLB 654 (2007) 87-91.
T1/2 = 350(50) ns
T (ns)
Differential cross sections and SF
Isomeric state
Ground state
27A MeV
(DWBA)
5A MeV
(DWBA)[1]
2.8 A MeV
(DWBA)[2]
G.S
0.14+0.04-0.04
0.25+0.03-0.07
Isomer
0.24+0.08-0.08
0.73+0.27-0.40
0.15~0.25
0.32~0.95
Fresco input file is provided by D.Y.Pang
[1] ]Phys.lett.B 682,391,2010.
[2] Phys.Rev.C 88,044619,2013
Error： 68% confidence
G.S SF is in consistent with previous results
Isomeric state ‘s SF is inconsistent
01+ G.S
Inutruder
02+ Isomer
normal
intruder
G.S
Isomer
reference
norm
al
(1) G.S: only get s-wave SF, could not get d-wave and p-wave content.
Consistent with
s other
d experimental
p
s d p results within error bar
42 Dominant dominant J.Phys.G 36,038001,2009;
Isomeric state: very small s-wave SF from experiment, small
content from
J.Phys.Gd-wave
2, L45,1976
F.C.Barke
(2)
33
34
32
56
2
theory,
might
dominate.
H.T.Fortune
and so intruder
53
15 states
32
25 7 not
68 dominant
Not
Phys.Rev.C 74,024301,2006; J.Phys.G
R.Sherrconsistent with other experimental results with error bar
038002,2009;
Phys.Rev.C83,044313,2011.
C.Romero-Redondo
Three –body model
?
10- 13-19 1513
23
68
?
G.Blanchon pp-RPA
25
18.5
0
19 Not
M.Dufour
58
74
dominant
Not
Phys.Rev.C 77,054313,2008.
dominant Phys.Rev.C 82,034313,2010.
NCSM
16
59
no
Not
No data
Nucl.Phys.A 836,242,2010.
Knock -out reaction
68
32
no
dominant
No data
Phys.Rev.Lett 85,266,2000;
Phys.Rev.Lett 96,032502,2006.
no
60 dominant
Not
Phys.Rev.lett 108,122501,2012.
Charge exchange
reaction
no
no
25
Transfer reaction
0.28
no
no
0.73 no
no uncertainty dominant
0.15~
0.25
no
no
0.32- no
0.95
no uncertainty uncertainty Phys.Rev.C 88,044619,2013
0.14
no
no
0.24 no
no D-wave?
Our result
no
Not
Phys.lett.B 682,391,2010.
Summary
 OP for 11Be+d are extracted from the same experiment
Global OP including 11Be density can reproduce angular distribution
Core excitation of 11Be is important
the effect of H percent in CD2 target are removed
 New experimental technical to detect isomeric state
implant----stop-----decay
get the angular distributions in smaller C.M system
 DWBA method is used to extract the s-wave SF
G.S : SF = 0.14+0.04-0.04, not in conflict with other experimental results
Isomeric state: SF = 0.24+0.08-0.08, Consistent with other experimental result
 ADWA calculations for these three sets data
 More theoretical calculations to explain our results
Intruder state
Normal state
Collaborators
Chen Jie, Ye Yanlin, Li Zhihuan, Li Qite, Ge Yucheng,
Jiang Dongxing, Hua Hui, Yang Zaihong, Sun Yelei,
Tian zheng yang,Li Jing, Jiang Wei, Zang Hongliang
Aoi, Ong Hooi Jin, Eiji Ideguchi, Tetsuya, Mana, Suzuki,
Tran Trong
Jenny lee, Wu Jin, Liu Hongna, Wen Chao
Pang Danyang
A.M.Moro
Test Results for PKU silicon detector
5.486 MeV
缺一张环形硅的测试图。
detected by
Energy spectrum of 241Am detected
by400 um Annular DSSD
5.443 MeV
Energy spectrum of
300 um DSSD
241Am
Energy resolution is about 0.5—0.6%
(FWHM).
Energy resolution is about 0.7—0.8%
(FWHM).
Dead layer is about 0.6 um silicon layer equivalence .
Provide by J.Chen
Time resolution of NaI(Tl) detector
OUT
NaI
ADC
N568B
trigger
FOUT
60Co
Plastic
CFD
CFD
delay
and
trigger
stop
TDC
start
Time resolution of NaI(Tl) detector is
about 1.7ns(FWHM).
The time signal will be recorded in the experiment, which will be used to identify
the delayed gamma events.
Give the uniform SF at different incident energies.
The decay from Ex = 2.68 MeV to 02+ , which can
not be distinguished from the direct population 02+ ,
can be ignored.
0.4%
99.6%
The gamma decay probability is proportional to
Er3, only 0.4% 1- state will decay to 02+ .
eq. 3C-16 of the Bohr Mottelson textbook.
Provided by Pro.Aoi-san
Therefore, we can reach our preliminary physical
goal with the thick target.
TOF (ns)
From Target CD2
From silicon detector
TDC: Common-stop mode
Proton: Most are from 0-degree
silicon detector
E(MeV)
PID in 0-degree telescope
10Be
11Be
PID with !(time cut)
12Be
4He
DSSD Energy
DSSD Energy
PID without proton-time cut
11Be
10Be
12Be
8Li
SSD1 Energy
PID with time cutCtarget
DSSD Energy
DSSD Energy
SSD1 Energy
PID with proton-time cut
4He
SSD1 Energy
SSD1 Energy
Carbon background
Without Carbon background
ΔE
ΔE
With Carbon background
Energy/MeV
Energy/MeV