1. Search for unbound excited states of proton rich nuclei
SAMURAI
9-10 March 2011
Search for unbound excited states of proton rich nuclei
Naohito IWASA
Department of Physics, Tohoku University

2. Motivation E(21+) and B(E2) in even-even nuclei
46Fe
48Fe
E(21+) and B(E2) in even-even nuclei
collectivity/shell structure
Systematical　studies
　magicity disappearance around 32Mg-32Ne
→ new magic number N=14, 16 in 22,24O
　B(E2) anomaly of 16,18C
Isotope
E(2+)
B(E2;↑)
42Cr
44Cr
46Cr
0.892
900±10
40Ti
42Ti
1.55
870±250
44Ti
1.08
650±160
preliminary
36Ca
3.02
（71±13)
36Ca
3.02
38Ca
2.21
96±21
40Ca
3.90
99±17
42Ca
1.52
420±30
32Ar
1.82
266±68
34Ar
2.09
240±40
36Ar
1.97
300±30
38Ar
2.17
130±10
40Ar
1.46
330±40
24Si, 28S (Tz=-2): small B(E2)
　 0gs+→21+: neutrons plays important role
　 subshell closure (Z=14,16) effect?
　 E(21+) are not high: not magic.
36Ca: B(E2): smallest in Ca isotopes
　 E(21+): 0.3MeV smaller than that of mirror nucleus 36S.
28S
1.51
28S
1.51
(102±16)
30S
2.21
324±41
32S
2.23
300±13
34S
2.13
212±12
36S
3.29
104±28
38S
1.29
235±30
22Si
24Si
1.88
(60±20)
24Si
1.88
(60±20)
26Si
1.80
356±34
28Si
1.78
326±12
30Si
2.24
215±10
32Si
1.94
113±33
34Si
3.33
85±33
36Si
1.40
190±60
20Mg
1.61
177±32
22Mg
1.25
370±130
24Mg
1.37
432±11
26Mg
1.81
305±13
28Mg
1.47
350±50
30Mg
1.48
295±26
32Mg
0.885
454±78
34Mg
0.656
631±126
18Ne
1.89
176±30
20Ne
1.63
340±30
22Ne
1.28
230±10
24Ne
1.98
170±60
26Ne
2.02
228±41
28Ne
1.32
132±23
30Ne
0.79
32Ne
0.72
16O
6.92
41±4
18O
1.982
45±2
20O
1.67
28±2
22O
3.17
21±8
24O
4.72
14C
7.01
18±3
16C
1.77
2.7±0.7
18C
1.62
4.3±1.0
20C
1.59
22C

3. Proposals Search for unbound excited states in Tz=-3 nuclei.
46Fe
48Fe
Search for unbound excited states in Tz=-3 nuclei.
Coulomb dissociation of 22Si
Search for 01+ and 21+ states in 34Ca using 2n-knockout reaction of 36Ca
Proton inelastic scattering of 42Cr, 48Fe
Isotope
E(2+)
B(E2;↑)
42Cr
44Cr
46Cr
0.892
900±10
40Ti
42Ti
1.55
870±250
44Ti
1.08
650±160
34Ca
36Ca
3.02
（71±13)
38Ca
2.21
96±21
40Ca
3.90
99±17
42Ca
1.52
420±30
32Ar
1.82
266±68
34Ar
2.09
240±40
36Ar
1.97
300±30
38Ar
2.17
130±10
40Ar
1.46
330±40
28S
1.51
(102±16)
30S
2.21
324±41
32S
2.23
300±13
34S
2.13
212±12
36S
3.29
104±28
38S
1.29
235±30
22Si
24Si
1.88
(60±20)
26Si
1.80
356±34
28Si
1.78
326±12
30Si
2.24
215±10
32Si
1.94
113±33
34Si
3.33
85±33
36Si
1.40
190±60
20Mg
1.61
177±32
22Mg
1.25
370±130
24Mg
1.37
432±11
26Mg
1.81
305±13
28Mg
1.47
350±50
30Mg
1.48
295±26
32Mg
0.885
454±78
34Mg
0.656
631±126
18Ne
1.89
176±30
20Ne
1.63
340±30
22Ne
1.28
230±10
24Ne
1.98
170±60
26Ne
2.02
228±41
28Ne
1.32
132±23
30Ne
0.79
32Ne
0.72
16O
6.92
41±4
18O
1.982
45±2
20O
1.67
28±2
22O
3.17
21±8
24O
4.72
14C
7.01
18±3
16C
1.77
2.7±0.7
18C
1.62
4.3±1.0
20C
1.59
22C

4. Coulomb dissociation of 22Si
B(E2↑)～200e2fm4: 16O+6p
B(E2↑)<100e2fm4: Z=14 subshell closure is significant
To determination of E(21+) and B(E2) in 22Si, we propose Coulomb dissociation experiment.
Z=14(subshell), N=8(magic)
Sp=1.2 MeV
No excited states are known
Mirror 22O: E(21+)=3.17MeV
N=14 in 22O: new magic number.
22Si
3.xx ?
???
24Si
1.88
(60±20)
24Si
1.88
60±20?
26Si
1.80
356±34
28Si
1.78
326±12
30Si
2.24
215±10
32Si
1.94
113±33
34Si
3.33
85±33
36Si
1.40
190±60 g
Doppler corrected g energy
energy of
excited states
Excitation
20Mg
invariant mass
22Si
breakup
virtual photon
2protons
charged particles Pb

5. Coulomb dissociation of 22Si
If excited states in 21Al exist between 1.4～2.0MeV,
18Ne+4p channel
3.17 2+
2.55
2.25
19Na+3p
18Ne+4p
Coulex
1.5
1.2
21Al+p
-0.1 0+
20Mg+2p
22Si
22O
Measurement of all the channel →　excitation cross section can be measured

6. Proposals Search for unbound excited states in Tz=-3 nuclei.
46Fe
48Fe
Search for unbound excited states in Tz=-3 nuclei.
Coulomb dissociation of 22Si
Search for 01+ and 21+ states in 34Ca using 2n-knockout reaction of 36Ca
Proton inelastic scattering of 42Cr, 48Fe
Isotope
E(2+)
B(E2;↑)
42Cr
44Cr
46Cr
0.892
900±10
40Ti
42Ti
1.55
870±250
44Ti
1.08
650±160
34Ca
36Ca
3.02
（71±13)
38Ca
2.21
96±21
40Ca
3.90
99±17
42Ca
1.52
420±30
32Ar
1.82
266±68
34Ar
2.09
240±40
36Ar
1.97
300±30
38Ar
2.17
130±10
40Ar
1.46
330±40
28S
1.51
(102±16)
30S
2.21
324±41
32S
2.23
300±13
34S
2.13
212±12
36S
3.29
104±28
38S
1.29
235±30
22Si
24Si
1.88
60±20?
26Si
1.80
356±34
28Si
1.78
326±12
30Si
2.24
215±10
32Si
1.94
113±33
34Si
3.33
85±33
36Si
1.40
190±60
20Mg
1.61
177±32
22Mg
1.25
370±130
24Mg
1.37
432±11
26Mg
1.81
305±13
28Mg
1.47
350±50
30Mg
1.48
295±26
32Mg
0.885
454±78
34Mg
0.656
631±126
18Ne
1.89
176±30
20Ne
1.63
340±30
22Ne
1.28
230±10
24Ne
1.98
170±60
26Ne
2.02
228±41
28Ne
1.32
132±23
30Ne
0.79
32Ne
0.72
16O
6.92
41±4
18O
1.982
45±2
20O
1.67
28±2
22O
3.17
21±8
24O
4.72
14C
7.01
18±3
16C
1.77
2.7±0.7
18C
1.62
4.3±1.0
20C
1.59
22C

7. Search for 01+ and 21+ states in 34Ca
MED=E(2+;Tz=-T)-E(2+;Tz=T)
Standard shell model: zero MED
exp. : |MED|≦0.1MeV
extremely large MED of 14O, 36Ca
21+ states are unbound
36Ca
The extremely large MED can be reproduced by shell model calc. with the sd shell isospin symmetric interaction USD using experimental proton and neutron SPE from the　 A = 17, T = 1/2 isospin doublet.
36Ca
14O
The new shell model predicted that the island of inversion in proton rich region may start at N = 14 in 34Ca.
Is Isospin violated ?
Experimental determination of E(2+) and B(E2) of 34Ca are desired.
P. Doornenbal et al., PLB 647 (2007) 237
Small correction of Z=14, N=14 gap
P. Doornenbal et al., PLB 647 (2007) 237

8. Search for 01+ and 21+ states in 34Ca
Mass formula (AUDI1995)
g.s. of 34Ca is bound, but 34Ca is not found yet.
Upper limit of the half life was measured to be 35ns at GANIL.
34Ca might have diproton radioactivity??
Coulomb diss. meth. cannot be used.
x B(E2)
We propose to measure the mass and E(21+) of 34Ca using 2n knockout reaction of 36Ca.
0.9
33K+p
-0.7
34Ca ?
32Ar+2p
32Ar
2n knockout
34Ca
36Ca
36Ca
breakup
9Be
2 protons
2 neutrons

9. Search for 01+ and 21+ states in 34Ca
36Ca + 9Be →34Ca*(gs, 2+)→32Ar+2p
Mass of 34Ca can be determined.
Mass of 33K is expected to be determined.
E(21+) is expected to be measured.
9Be(36Ca,34Ca) 2+ g?
0.9
33K+p 0+
-0.7
34Ca
not found
seems to be unbound
2 proton decay
32Ar+2p
E(21+) =～3MeV→34Ca is not in island of inversion
～1MeV→34Ca is in island of inversion

10. Proposals Search for unbound excited states in Tz=-3 nuclei.
46Fe
48Fe
Search for unbound excited states in Tz=-3 nuclei.
Coulomb dissociation of 22Si
Search for 01+ and 21+ states in 34Ca using 2n-knockout reaction of 36Ca
Proton inelastic scattering of 42Cr, 48Fe
Isotope
E(2+)
B(E2;↑)
42Cr
44Cr
46Cr
0.892
900±10
40Ti
42Ti
1.55
870±250
44Ti
1.08
650±160
36Ca
3.02
（71±13)
38Ca
2.21
96±21
40Ca
3.90
99±17
42Ca
1.52
420±30
32Ar
1.82
266±68
34Ar
2.09
240±40
36Ar
1.97
300±30
38Ar
2.17
130±10
40Ar
1.46
330±40
28S
1.51
(102±16)
30S
2.21
324±41
32S
2.23
300±13
34S
2.13
212±12
36S
3.29
104±28
38S
1.29
235±30
22Si
24Si
1.88
60±20?
26Si
1.80
356±34
28Si
1.78
326±12
30Si
2.24
215±10
32Si
1.94
113±33
34Si
3.33
85±33
36Si
1.40
190±60
20Mg
1.61
177±32
22Mg
1.25
370±130
24Mg
1.37
432±11
26Mg
1.81
305±13
28Mg
1.47
350±50
30Mg
1.48
295±26
32Mg
0.885
454±78
34Mg
0.656
631±126
18Ne
1.89
176±30
20Ne
1.63
340±30
22Ne
1.28
230±10
24Ne
1.98
170±60
26Ne
2.02
228±41
28Ne
1.32
132±23
30Ne
0.79
32Ne
0.72
16O
6.92
41±4
18O
1.982
45±2
20O
1.67
28±2
22O
3.17
21±8
24O
4.72
14C
7.01
18±3
16C
1.77
2.7±0.7
18C
1.62
4.3±1.0
20C
1.59
22C

11. Search for 21+ states in 42Cr, 46Fe
42Cr: Z=24, N= Ca+4p-2n
Sp=1.11MeV(mass formula)
No excited states are known.
Mirror 42Ar: E(2+)=1.21MeV
46Fe: Z=26, N=20(magic)
40Ca+6 protons configuration?
Sp=1.42MeV (mass formula)
No excited states are known.
Mirror 46Ca: E(2+)=1.35MeV
2.48 2+
2.57 4+
(3-,4+)
2.41
2.42 0+
(1.42)
1.21
1.35
(1.11) 2+ 2+
45Mn+p
41V+p
0.360
40Ti+2p 0+
44Cr+2p 0+
42Cr
42Ar
46Fe
46Ca

12. Experimental Setup High resolution mode of SAMURAI.
DALI 2 for g measurement
Pb, Be
Liq. H2targets
22Si, 36Ca,…
3×2 SSD
(xyu, xyv)
ICF, FDC, plastic
PDC, plastic
2 protons
20Mg, 32Ar,…
SSD should be in vac. chamber.
→breakup events and breakup
positions are identified
Focus: good mass res.
Less influence of MS
Target chamber, SSD and SSD chamber should be constructed.

13. Yield estimation 22Si @250AMeV 100cps from 100pnA 36Ar @400AMeV
100cps from 33pnA
Assuming σCx～10mb at 250AMeV
250AMeV
3kcps 36Ca from 40pnA
purity ～20% limit: 2kcps
2n knockout cross section: 0.1mb
target 100mg/cm2 thick 9Be
efficiency: 40% (Erel=3～4MeV)
48events/day～330 events/week
Target 200mg/cm2 thick Pb
22Si+Pb→20Mg+2p
coincidence efficiency
40% (Erel～3MeV, rough*)
20 events/day ～ 140 events/week
*We use simulation results of 7Be+p
coincidence efficiency of KaoS at GSI.

14. Yield estimation for 42Cr, 46Fe
0.04cps from 30pnA
10 times higher intensity beam is available*, (p,p’) measurement is possible.
0.4cps 42Cr beam
Target 200mg/cm2 Liq. H2
σ= 5mb, 80% coin.eff .
16 events/d = 116 events/week
g eff.: 20% 29 events/week
0.007cps from 30pnA
60 times higher intensity beam is available*, (p,p’) measurement is possible.
0.4cps 46Fe beam
Target 200mg/cm2 Liq. H2
σ= 5mb, 80% coin. eff.
16 events/d = 116 events/week
g eff.: 20% events/week
* 1pmA 84Kr beam will be available.
For B(E2) measurement, intensity of several ten particle/sec is necessary.

15. Summary
Coulomb dissociation reaction, knockout reaction and proton inelastic scattering are powerful tool to study collectivity and nuclear structure.
Coulomb dissociation of 22Si into 20Mg+2p may provide information on Z=14 subshell closure near the drip line.
From an experiments of 2n knockout reaction of 36Ca, mass and E(2+) of 34Ca are expected to be determined. The question why 34Ca is not found is expected to be solved.
Proton inelastic scattering experiments of 42Cr and 46Fe can be performed when high-intensity 84Kr beam is available.