SpectroscopyofNeutronDeficient...
Transcript of SpectroscopyofNeutronDeficient...
Spectroscopy of Neutron-‐‑Deficient Nuclei Near the Z=82 Shell Closure
Outline q Introduc2on & Mo2va2on q Symmetric Fusion Reac2ons as a tool for spectroscopy studies q Recent results on neutron-‐deficient 179,180Tl nuclides using the Recoil Decay Tagging technique, FMA & Gammasphere
q Outlook & Conclusions
2
Introduction & Motivation
ü 179Tl is 24 neutrons away from the stable 203Tl
proton emi-er
ü tes2ng ground for studying the phenomenon of shape coexistence interplay between microscopic shell effects, such as the occurrence of large gaps in the single-‐par2cle energies and the occupa2on of high-‐j intruder orbitals
G.D. Dracoulis, Phys. Scr. T88 (2000) 54
188Pb
K. Heyde and J.L. Wood, Rev. Mod. Phys. 83 (2011) 1467
Y. Litvinov et al., Nucl. Phys. A756 (2005) 3
A. Thornthwaite et al., Phys. Rev. C86 (2012) 064315
q define the mass surface at the drip-‐line
π(h9/2)(oblate) π(i13/2)(prolate) π(i13/2)(oblate) π(d3/2)-‐1 π(s1/2)-‐1
π(h11/2)-‐1 11/2-‐
11/2-‐
9/2-‐
3/2+
1/2+
13/2+ 13/2+
Neutron Number
177Tl
Introduction & Motivation – cont. q 181-‐195Tl – ü spherical ground state – 1/2+ (s1/2) ü oblate-‐deformed isomer – 9/2-‐ (h9/2) ü prolate-‐deformed -‐ low-‐Ω, i13/2 orbital
oblate-‐deformed -‐ high-‐Ω, i13/2 orbital
q 177Tl (N=96) – J.L. Poli et al., PRC 59 (1999) ü spherical ground state – 1/2+ (s1/2) ü spherical isomer – 11/2-‐ (h11/2) q 179Tl (N=98) ü K. Toth et al., PRC 58 (1990) 1310 ü R. Page et al., PRC 53 (1996) 660 ü M. Rowe et al., PRC 65 (2009) 054310 ü A. Andreyev et al., JP G37 (2010) 035102 –
only the decay of an isomer
? 179Tl
5
Neutron-‐‑deficient Au nuclei (Z=79)
F.G. Kondev et al., PLB 512 (2001)
q low-‐J ground state/high-‐J isomer q only 11/2-‐ state known in 175Au
179Tl
6
Experimental Challenges q Conventional Heavy-‐‑ion fusion-‐‑evaporation reactions to get there, but ...
ü charged particle emission is significant – the cross section is fragmented – lower yield of the nuclide you want
ü fission process (CN fissility ~Z2/A1/3 – 180Hg-‐‑>238U) -‐‑ depletion of high-‐‑l values – limit population of states at high spin -‐‑ huge unwanted background
ü minimizes the fission probability ü enhanced fusion cross section -‐‑
minimizes the fragmentation of reaction channel
q allows: ü more beam on target ü less restrictive gating
BoPom line: you make more of the stuff you want!
q Symmetric reactions near the barrier
Experiments & Techniques
PGAC
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ü 90Zr + 90,92Zr@180Hg ü 90Zr + 82Mo@182Pb ü 89Y + 90Zr@179Au ü 84Sr + 92-‐96Mo@176-‐180Hg ü 89Y + 92Mo@181Tl@375 MeV X-‐array
one “Super-‐Clover” & four 70 X 70 mm Clovers
179Tl: α-decay properties
179Tl
175Au
171Ir
g.s. isomer
ε+β+11%
ε+β+
22%
179Hg (1p1n)
9
179Tl: lifetimes
2
5000 6000 7000100
101
102
103
104
105
Eα1 (keV)
Cou
nts 71
946556
6431
6286A=179 gated
0 < Δtα1 < 4 s
FIG. 1: Energy spectrum of first-generation ↵-decay eventswith a requirement that the decay occurred within 4 s of amass A=179 implant.
the PGAC to the DSSD. The data were then sorted inprompt (±100 ns) �-� and ↵��, and delayed ↵�↵ coin-cidence histograms, gated in various ways on the energyand time information from the DSSD.
The energy calibration of the DSSD was carried out us-ing known ↵ lines of 175Pt (5960(3) keV), 176Pt (5747(5)keV), 179Hg (6286 (4) keV) and 180Hg (6119(4) keV) thatwere produced in the present experiment. The energyand e�ciency calibrations of the Gammasphere and theGe CLOVER array at the FMA focal plane were per-formed using 152Eu and 182Ta radioactivity sources.
A. Decay of 179,179mTl
The energy spectrum of first-generation ↵-decay eventswith an additional requirement that the decay occurredwithin 4 s of a mass A=179 implant is shown in Fig. 1.The most intense peak at 6286 keV is assigned to the de-cay of 179Hg, while those at 6556 keV and 7194 keV areassociated with the decays of the ground and isomericstates of 179Tl, respectively. The measured energies arein good agreement with those reported in the previousstudies [17–20], as summarized in Table I. The peak at6431 keV is associated with the decay of the 175Au nu-clide, a daughter of 179Tl. Its presence in the spectrumis because some of the parent ↵ decays can escape theDSSD undetected, coupled with the shorter (hundred ofmilliseconds) lifetimes involved (see below in the text).The 179Tl and 179mTl half-lives were deduced from timespectra produced by gating on the corresponding first-generation ↵ decays, as shown in Fig. 2a and b, respec-tively. Our value for the ground state half-life is in agood agreement with that reported by Rowe et al. [18],but it is of better precision. However, it is much longer
1000 2000 3000 4000
10–1
100
101
Time (ms)
Cha
nnel
s
a)T1/2=476(19) ms
2 4 6 8 10 12 1410–1
100
101
102
103
Time (ms)
Cha
nnel
s
b)T1/2=1.36(4) ms
100 300 500 700 900 1100
10–1
100
101
Time (ms)
Cha
nnel
s
c)T1/2=188 (12) ms
100 300 500 700 900
10–1
100
101
Time (ms)
Cha
nnel
s
d)T1/2=124 (8) ms
6556α1(t) 7194α1(t)
6556α1-6431α2(t) 7194α1-6431α2(t)
FIG. 2: a) and b) time spectra produced by gating on firstgeneration E↵1=6556 keV (179Tl) and 7194 keV (179mTl)lines, respectively c) and d) time spectra produced by gatingon the second-generation E↵2=6431 keV line with additionalrequirements that it is correlated with the first-generationE↵1=6556 keV and 7194 keV decays, respectively.
when compared to the values reported in Refs. [20, 21].The measured half-life for the isomeric state is consistentwith the literature values, as presented in Table I.
Figure 3 shows Gammasphere �-ray spectra correlatedwith the 6556 keV and 7194 keV ↵ decays. As can beseen, some of the � rays in the two spectra are identical,thus implying that the isomer and the ground state areconnected via a �-ray branch. Unfortunately, it was notpossible to establish the connecting �-ray transition(s),presumably because of the long lifetime of the isomer. Asa consequence, it was not possible to directly determinethe excitation energy of the isomer. However, interpo-lation of the known excitation energies of 807 (18) keV(177Tl) [22], 895.9 (10) keV (181Tl) [23, 24] and 907.4(4) keV (183Tl) [25] for the I⇡=11/2� state associatedwith the spherical ⇡h11/2 configuration, allowed a valueof 860 (7) keV to be deduced for the 179mTl excitationenergy. As can be seen in Figure 3, the 227 keV and452 keV gamma rays are correlated only with E↵1=6556keV (179Tl), but not with E↵1=7194 keV (179mTl), andare therefore placed above the ground state, as shown inFig. 4. It is worth noting that � rays of similar energies(258 keV and 565 keV) were placed above the I⇡=1/2+
ground state in the neighboring isotope 181Tl [23, 24].The 231, 256, 340, and 455 keV � rays, and tentativelythe 189 keV one, precede the isomer, as evident fromFig. 3b. While the 231, 256 and 455 keV � rays were
1/2+ (g.s) 11/2-‐ (iso)
179Tl – g.s. 2
5000 6000 7000100
101
102
103
104
105
Eα1 (keV)
Cou
nts 71
946556
6431
6286A=179 gated
0 < Δtα1 < 4 s
FIG. 1: Energy spectrum of first-generation ↵-decay eventswith a requirement that the decay occurred within 4 s of amass A=179 implant.
the PGAC to the DSSD. The data were then sorted inprompt (±100 ns) �-� and ↵��, and delayed ↵�↵ coin-cidence histograms, gated in various ways on the energyand time information from the DSSD.
The energy calibration of the DSSD was carried out us-ing known ↵ lines of 175Pt (5960(3) keV), 176Pt (5747(5)keV), 179Hg (6286 (4) keV) and 180Hg (6119(4) keV) thatwere produced in the present experiment. The energyand e�ciency calibrations of the Gammasphere and theGe CLOVER array at the FMA focal plane were per-formed using 152Eu and 182Ta radioactivity sources.
A. Decay of 179,179mTl
The energy spectrum of first-generation ↵-decay eventswith an additional requirement that the decay occurredwithin 4 s of a mass A=179 implant is shown in Fig. 1.The most intense peak at 6286 keV is assigned to the de-cay of 179Hg, while those at 6556 keV and 7194 keV areassociated with the decays of the ground and isomericstates of 179Tl, respectively. The measured energies arein good agreement with those reported in the previousstudies [17–20], as summarized in Table I. The peak at6431 keV is associated with the decay of the 175Au nu-clide, a daughter of 179Tl. Its presence in the spectrumis because some of the parent ↵ decays can escape theDSSD undetected, coupled with the shorter (hundred ofmilliseconds) lifetimes involved (see below in the text).The 179Tl and 179mTl half-lives were deduced from timespectra produced by gating on the corresponding first-generation ↵ decays, as shown in Fig. 2a and b, respec-tively. Our value for the ground state half-life is in agood agreement with that reported by Rowe et al. [18],but it is of better precision. However, it is much longer
1000 2000 3000 4000
10–1
100
101
Time (ms)
Cha
nnel
s
a)T1/2=476(19) ms
2 4 6 8 10 12 1410–1
100
101
102
103
Time (ms)
Cha
nnel
s
b)T1/2=1.36(4) ms
100 300 500 700 900 1100
10–1
100
101
Time (ms)
Cha
nnel
s
c)T1/2=188 (12) ms
100 300 500 700 900
10–1
100
101
Time (ms)
Cha
nnel
s
d)T1/2=124 (8) ms
6556α1(t) 7194α1(t)
6556α1-6431α2(t) 7194α1-6431α2(t)
FIG. 2: a) and b) time spectra produced by gating on firstgeneration E↵1=6556 keV (179Tl) and 7194 keV (179mTl)lines, respectively c) and d) time spectra produced by gatingon the second-generation E↵2=6431 keV line with additionalrequirements that it is correlated with the first-generationE↵1=6556 keV and 7194 keV decays, respectively.
when compared to the values reported in Refs. [20, 21].The measured half-life for the isomeric state is consistentwith the literature values, as presented in Table I.
Figure 3 shows Gammasphere �-ray spectra correlatedwith the 6556 keV and 7194 keV ↵ decays. As can beseen, some of the � rays in the two spectra are identical,thus implying that the isomer and the ground state areconnected via a �-ray branch. Unfortunately, it was notpossible to establish the connecting �-ray transition(s),presumably because of the long lifetime of the isomer. Asa consequence, it was not possible to directly determinethe excitation energy of the isomer. However, interpo-lation of the known excitation energies of 807 (18) keV(177Tl) [22], 895.9 (10) keV (181Tl) [23, 24] and 907.4(4) keV (183Tl) [25] for the I⇡=11/2� state associatedwith the spherical ⇡h11/2 configuration, allowed a valueof 860 (7) keV to be deduced for the 179mTl excitationenergy. As can be seen in Figure 3, the 227 keV and452 keV gamma rays are correlated only with E↵1=6556keV (179Tl), but not with E↵1=7194 keV (179mTl), andare therefore placed above the ground state, as shown inFig. 4. It is worth noting that � rays of similar energies(258 keV and 565 keV) were placed above the I⇡=1/2+
ground state in the neighboring isotope 181Tl [23, 24].The 231, 256, 340, and 455 keV � rays, and tentativelythe 189 keV one, precede the isomer, as evident fromFig. 3b. While the 231, 256 and 455 keV � rays were
476 (19) ms present
415 (55) ms – LBNL 230 (40) ms – ANL (1998) 160 (+90-‐40) ms – GSI (1993)
179Tl – isomer good agreement with previous measurements
10
175Au: lifetimes 2
5000 6000 7000100
101
102
103
104
105
Eα1 (keV)
Cou
nts 71
946556
6431
6286A=179 gated
0 < Δtα1 < 4 s
FIG. 1: Energy spectrum of first-generation ↵-decay eventswith a requirement that the decay occurred within 4 s of amass A=179 implant.
the PGAC to the DSSD. The data were then sorted inprompt (±100 ns) �-� and ↵��, and delayed ↵�↵ coin-cidence histograms, gated in various ways on the energyand time information from the DSSD.
The energy calibration of the DSSD was carried out us-ing known ↵ lines of 175Pt (5960(3) keV), 176Pt (5747(5)keV), 179Hg (6286 (4) keV) and 180Hg (6119(4) keV) thatwere produced in the present experiment. The energyand e�ciency calibrations of the Gammasphere and theGe CLOVER array at the FMA focal plane were per-formed using 152Eu and 182Ta radioactivity sources.
A. Decay of 179,179mTl
The energy spectrum of first-generation ↵-decay eventswith an additional requirement that the decay occurredwithin 4 s of a mass A=179 implant is shown in Fig. 1.The most intense peak at 6286 keV is assigned to the de-cay of 179Hg, while those at 6556 keV and 7194 keV areassociated with the decays of the ground and isomericstates of 179Tl, respectively. The measured energies arein good agreement with those reported in the previousstudies [17–20], as summarized in Table I. The peak at6431 keV is associated with the decay of the 175Au nu-clide, a daughter of 179Tl. Its presence in the spectrumis because some of the parent ↵ decays can escape theDSSD undetected, coupled with the shorter (hundred ofmilliseconds) lifetimes involved (see below in the text).The 179Tl and 179mTl half-lives were deduced from timespectra produced by gating on the corresponding first-generation ↵ decays, as shown in Fig. 2a and b, respec-tively. Our value for the ground state half-life is in agood agreement with that reported by Rowe et al. [18],but it is of better precision. However, it is much longer
1000 2000 3000 4000
10–1
100
101
Time (ms)C
hann
els
a)T1/2=476(19) ms
2 4 6 8 10 12 1410–1
100
101
102
103
Time (ms)
Cha
nnel
s
b)T1/2=1.36(4) ms
100 300 500 700 900 1100
10–1
100
101
Time (ms)
Cha
nnel
s
c)T1/2=188 (12) ms
100 300 500 700 900
10–1
100
101
Time (ms)C
hann
els
d)T1/2=124 (8) ms
6556α1(t) 7194α1(t)
6556α1-6431α2(t) 7194α1-6431α2(t)
FIG. 2: a) and b) time spectra produced by gating on firstgeneration E↵1=6556 keV (179Tl) and 7194 keV (179mTl)lines, respectively c) and d) time spectra produced by gatingon the second-generation E↵2=6431 keV line with additionalrequirements that it is correlated with the first-generationE↵1=6556 keV and 7194 keV decays, respectively.
when compared to the values reported in Refs. [20, 21].The measured half-life for the isomeric state is consistentwith the literature values, as presented in Table I.
Figure 3 shows Gammasphere �-ray spectra correlatedwith the 6556 keV and 7194 keV ↵ decays. As can beseen, some of the � rays in the two spectra are identical,thus implying that the isomer and the ground state areconnected via a �-ray branch. Unfortunately, it was notpossible to establish the connecting �-ray transition(s),presumably because of the long lifetime of the isomer. Asa consequence, it was not possible to directly determinethe excitation energy of the isomer. However, interpo-lation of the known excitation energies of 807 (18) keV(177Tl) [22], 895.9 (10) keV (181Tl) [23, 24] and 907.4(4) keV (183Tl) [25] for the I⇡=11/2� state associatedwith the spherical ⇡h11/2 configuration, allowed a valueof 860 (7) keV to be deduced for the 179mTl excitationenergy. As can be seen in Figure 3, the 227 keV and452 keV gamma rays are correlated only with E↵1=6556keV (179Tl), but not with E↵1=7194 keV (179mTl), andare therefore placed above the ground state, as shown inFig. 4. It is worth noting that � rays of similar energies(258 keV and 565 keV) were placed above the I⇡=1/2+
ground state in the neighboring isotope 181Tl [23, 24].The 231, 256, 340, and 455 keV � rays, and tentativelythe 189 keV one, precede the isomer, as evident fromFig. 3b. While the 231, 256 and 455 keV � rays were
1/2+ (g.s) 11/2-‐ (iso) similar, but not iden2cal!
188 (12) ms – 124 (8) ms
158 (3) ms using 6432α(t)
F.G. Kondev et al., PLB 512 (2001)
3
0
4
8
12
(189
)
256
340
227
\ /
231
\/45
2 455
a)
100 200 300 400 5000
4
8
12
Energy (keV)
Cou
nts
(189
) 256
340
231
455
b)
Tl X
-rays
FIG. 3: a) and b) prompt �-ray spectra, correlated with the6556 keV (179Tl) and 7194 keV (179mTl) ↵ lines, respectively.
found to be in a prompt coincidence, the 340 keV gammaray was in prompt coincidence only with the latter two,but not with the 231 keV � ray.
B. Decay of 175,175mAu
In our previous studies [26], only the decay of 175mAuwas reported with E↵=6.43 MeV and T1/2=143 (8)ms. Our findings were confirmed in the recent workof Andreyev et al. [17], where correlations between theE↵1=7207 (5) keV (179mTl) and E↵1=6432 (5) keV(175mAu) ↵ lines were observed, and T1/2=138 (5) mswas reported for the later, but they did not provide in-formation of the ground state. Rowe et al. [18] assigneda E↵=6438 keV to 175Au, as they reported that it wascorrelated with both the 179Tl and 179mTl ↵ decays. Asecond ↵ line with E↵=6412 keV was found to be cor-related with the 5717 (10) keV one, associated with thedecay of 171Ir ground state [18]. Page et al. [19] assigned6438 (9) keV ↵ line to decay of 175Au.
Present work resolved the ambiguities that existed forthe decay of 175,175mAu. Figure 5a and 5b show second-generation alpha spectra produced by gating on first-
generation E↵1=6556 keV (179Tl) and 7194 keV (179mTl).The two spectra look nearly identical, with the 6431 keV↵ line associated with 175Au and the 5965 keV one withthe decay of 175Pt. Importantly, third-generation spec-tra, produced by double-gating on 6556↵1-6431↵2 (Fig-ure 4c) and 7194↵1-6431↵2 (Figure 4d) clearly indicatethat di↵erent third-generation ↵ lines with E↵=5728 keVand 5958 keV are correlated with the 6431 keV one. Thisimplies that both the ground state and the isomer in175Au are depopulated by ↵ decays with nearly-identicalenergies. The half-lives of 188 (12) ms and 124 (8) mswere obtained for the ground state and the isomer in175Au, as shown in Figure 2c and 2d, respectively, whichare similar, but not identical. Clearly, our previously re-ported value [26] contains contributions from both theisomer and the ground state. If one takes the excitationenergy of the isomer in 179Tl as 860 (7) keV and the mea-sured here ↵ energies, then the excitation energy of 207(14) keV can be obtained for the isomer in 175Au.The presence of 5965 keV ↵ line in the spectra shown in
Figure 5a and 5b, suggests that both 175Au and 175mAuhave EC-�+ branches. Given the known ↵-decay branch-ing ratio of b↵= 64 (5)% for 175Pt [41], one can deduceb↵= 89(3)% and 78 (4)% for 175Au and 175mAu, respec-tively. The deduced in the present work b↵ value for175mAu is somewhat lower compared to that of 90 (3)%reported by Andreyev et al. [17].Three ↵ lines were known in the decay of 175Pt and
the present work confirm that. A half-life of 2.30(1) swas obtained for 175Pt, which is in good agreement withthe previous studies, as shown in Table I. The stronger(favorite) decay feeds the 7/2� level of the 5/2� bandin the daughter 171Os nuclide, while the week 5841(8)keV feeds the 9/2� band member. Gamma-ray spectradetected in the CLOVER array in coincidence with the5961 and 5841 keV ↵ lines are shown in Figure. 6. Themeasured �-ray energies are in agreement with those re-ported in [28, 39]. However, the energies of 133.5 keVand 209.8 keV gamma rays are systematically higher thanthose of 130.78 and 207.64 keV reported in the in-beamstudies [42].
C. Decay of 171,171mIr
While a somewhat detailed data are known for the de-cay of 171mIr, only little is known for the decay of theground state. The present work clearly establishes thatthe 5728 keV line is associated with the 171Ir, as evi-dent of the correlations with 179Tl!175Au!171Ir, seenin Fig. 2. The measured half-life is in agreement with thevalue reported by Rowe at el.[18], but it is more precise.The observed 5958 keV ↵ line for the isomer is some-what larger compared to that reported by Andreyev etal. [17], but it is in agreement with that observed by Pageet al. [19]. We do confirm that this decay feeds the ex-cited state that decays via a 92 keV �-ray transition tothe 9/2� ground state. It is therefore possible that the
11
179Tl: in-‐‑beam data
ü connec2on between the 11/2-‐ isomer and the 1/2+ g.s.
similar to 181Tl: M.P. Carpenter et al.
7182α
6556α
6556α
7182α
4
1/2+
11/2-
(3/2+)
(5/2+)
1/2+
1/2+
1/2+
9/2-
11/2-
11/2-
11/2-
860(7)
0
0
0
0
207(14)
207(17)
9289(19)
227a
452a 227
679
92a
6556_
5728_
6431_
7194_
5958_
6431_
179Tl
175Au
171Ir
167Re
476 ms
1.36 ms
188 ms124 ms
3.1 s1.51 s
3.4 s5.9 s
%b_=100
%b_=50
%b_=78
%b_=89
%b_=54%b
_~100
FIG. 4: Schematic decay chain originating from 179Tl and terminating in 163Ta.
5600 6000 6400
5
10
15
20
25
Cou
nts
Eα3 (keV)
0 < Δt(α2-α3) < 40 s6556α1-6431α2 gated(c)
5728
5600 6000 6400
101
102
Eα2 (keV)
Cou
nts
(a) 6556α1 gated0 < Δt(α1-α2) < 2 s
5965
6431
5600 6000 6400
101
102
(b) 7194α1 gated0 < Δt(α1-α2) < 2 s
5965
6431
Cou
nts
5600 6000 64000
10
20
30
40
Cou
nts
Eα3 (keV)
(d) 7194α1-6431α2 gated0 < Δt(α2-α3) < 20 s59
58
Eα2 (keV)
FIG. 5: a) and b) ↵ spectra produced by gating on first-generation E↵1=6556 keV (179Tl) and 7194 keV (179mTl) lines,respectively c) and d) ↵ spectra produced by gating on the second-generation E↵2=6431 keV line with additional requirementsthat it is correlated with the first-generation E↵1=6556 keV and 7194 keV decays, respectively.
5958 keV line is a sum of the real ↵ and the conversionelectrons. If one consider the binding energy of 20.3 keV,then E↵= 5938 (8) keV would be expected. Using the
deduced excitation energy of 207 (14) keV for 175mAuand assuming the same energy of 6431 (8) keV, one candeduce the excitation energy of the isomer in 171mIr as
Theoryi
Exp
Theoryi
Exp
i TBRT
TTHF
2/1
2/1
2/1
2/1 /)(==
α TheoryT 2/1 M.A. Preston, Phys. Rev. 71 (1947) 865
HF < 4 favorite (ΔL=0)decay
1.12 (6) 0.50 (3)
2.16 (17) 1.63 (19)
2.2 (4) 0.36 (6) %bα~15%
1/2+ 11/2-‐
Odd-‐‑odd Tl nuclei? q 181-‐198Tl (N=100-‐117) isotopes ü spherical ground state – 1/2+ (s1/2) ü oblate-‐deformed isomer – 9/2-‐ (h9/2) q 179-‐199Pb (Z=82) ü spherical ground state – 3/2-‐ (p3/2) ü spherical isomer – 13/2+ (i13/2)
q odd-‐odd Tl: ü low (2-‐) and high-‐spin (7+) isomers
but … changes in structure of neutron-‐deficient Pb below 181Pb
ü Jπ=9/2-‐ instead of 3/2-‐ , associated with deforma2on related effects ü do such changes affect Tl nuclides?
(3-‐)
(3-‐)
(9+)
(8+) 212 175
6.22 6.28
6.12 6.08
176Au
172Ir
J.T.M. Goon, PhD thesis, UT
T1/2=1.05 s T1/2=1.4 s
84Sr + 94Mo@178Hg (pn)176Au Gammasphere & FMA
A=176
gammasphere
15
180Tl: α decay
176Pt 176Au ε+β+
180Tl (1n)
180Hg (1p)
%α = 80 (8) %ε+β+=20 (8)
α
172Ir
(3-‐)
(3-‐)
(9+)
(8+) 212 175
6.29 6.28 MeV
6.12 6.08
176Au
αε+β+
5.76 MeV α
176Pt
16
180Tl: α-γ coincidences
ü decay of a single state in 180Tl 16
Au X-‐rays known in 176Au
180Tl: Iπ=4-‐ and 5-‐: π1/2+ (s1/2) x ν9/2-‐ (h9/2) -‐ favored α-‐decay 176Au: Iπ=3-‐ and 4-‐: π1/2+ (s1/2) x ν7/2-‐ (ff/2)
(4-‐)
180Tl: in-‐‑beam gamma rays
Conclusions & Outlook
q symmetric HI fusion reac2ons at energies near the Coulomb barrier in conjunc2on with the RDT technique are powerful tool to study proton-‐rich nuclei at the edge of stability
q 179Tl: long-‐lived 1/2+ g.s. and a shorter-‐lived 11/2-‐ isomer, both associated with spherical shape – decay correla2ons were essen2al; established the “missing” g.s. of 175Au
q 180Tl: a single-‐decaying state; Iπ=(4,5)-‐: π1/2+ (s1/2) x ν9/2-‐(h9/2)
q future: life2me measurements for the prolate-‐deformed bands known in Au/Tl isotopes to ascertain deforma2on and shape – using DSAM & direct 2ming technique using LaBr3 scin2lla2on detectors; digital Gammasphere and DSSD
Collaborators
Supported by the Office of Nuclear Physics, U.S. DOE
M.P. Carpenter, S. Zhu, R.V.F. Janssens, I. Ahmad, B.B. Back, P.F. Bertone, J. Chen, C.J. Chiara, C.A. Copos, J.P. Greene, G. Henning, C.R. Hoffman, B.P. Kay, T.L. Khoo, T. Lauritsen, E.A. McCutchan, C. Nair, A.M. Rogers, D. Seweryniak
Argonne National Laboratory
D.J. Hartley US Naval Academy
Thank you!