Z = 37 - 62

335 Pages·2003·2.75 MB·English

by  V. V. Voronov, A. I. Vdovin, A. N. Storozhenko (auth.), H. Schopper (eds.)

IX
Introduction
This volume contains experimental information about the properties of excited states of atomic
nuclei with Z ranging from 37 to 62. Chapter 4 includes spectroscopic data for nuclides of Rb,
37
Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd,and InandChapter5includes
38 39 40 41 42 43 44 45 46 47 48 49
spectroscopic data for nuclides of Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd,
50 51 52 53 54 55 56 57 58 59 60
Pm, and Sm.
61 62
This is the region of the so-called middle-heavy nuclei. At the lower boundary it contains
nuclides with the magic number of neutrons N = 50 and/or ”quasi-magic” number of protons
Z =40. At the center one can find a long chain of stable or long-living isotopes of Sn with magic
proton number Z = 50. At the higher boundary properties of the nuclei are strongly influenced
by the vicinity of the next neutron magic number N =82. That is why this regioncontains many
stableorlong-livingnuclides. Manyofthemwhicharenearthebeta-stabilitylinehaveaspherically
symmetrical shape in their ground state and low-energy excited states. This is especially true for
the nuclides with a magic number of protons or neutrons. At higher excitation energies the shape
of a nucleus can differ from that at lower energies. The shape coexistence effect is established in
many nuclei in the region. Moreover, a new generation of γ-ray detectors produces a wealth of
dataaboutsuperdeformedbands athighexcitationenergies. The superdeformedbands havebeen
foundinnucleifromthreedistinctregionsnearA=80,130and150. Attheveryendoftheregion
one can find nuclei with obvious fingerprints of a rotational motion in the low-lying part of their
spectra. They are of ellipsoidal shape in their ground states.
Ashortreviewofthemoderntheoreticalapproachesinnuclearstructurephysicsisgiveninthe
Chapter 1. We only mention here as the most fundamental methods at the moment the Hartree-
Fock and the Hartree-Fock-Bogoliubov methods, which are applied to analyze the properties of
groundstatesaswellasexcitedstates. Sometimestheshellmodelisalsousedtothisaim. Lessfun-
damental but more widely applied are microscopic nuclear structure models like the quasiparticle
- phonon nuclear model and a theory of finite Fermi-systems. They are successful in the expla-
nation of the properties of semi-magic and neighboring nuclei. The interacting boson model and
its numerous modifications that belong to a class of so-called”algebraic”approachesare the most
effective in describing the properties of low-lying collective states in transitional (or soft) nuclei.
To treat odd-mass or odd-odd nuclei models considering them as systems of one or two nucleons
coupled with an even-even core are applied. To understand the spectroscopy of deformed nuclei
the cranked Hartree - Fock - Bogoliubov method or the ”deformed” version of the quasiparticle -
phonon model combined with a phenomenological description of nuclear rotation is used.
General characteristics of the selected data
The objective of this review is to present well-established spectroscopic information about the
nucleiinquestion(37≤Z ≤62). The availableexperimentaldataonthe levelpropertiesarevast.
Here we present data only about those excited levels for which the major characteristics - energy,
Landolt-Bo¨rnstein
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X Introduction
spin and parity - are determined unambiguously. The data have basically been derived from the
“Nuclear Data Sheets” journal and “Evaluated Nuclear Structure Data Files”.
The number of unambiguously determined levels in a nucleus varies from one or two to several
dozens and sometimes more than one hundred. Due to limitation in size of this review we have
been forced to include data only about nuclei with a half-life T1/2 ≥ 10 h in the ground, or
isomeric, state for nuclei of the region 37 ≤ Z ≤ 49, and T1/2 ≥ 2 d for nuclei of the region
50≤Z ≤62. Moreover,informationaboutnucleiwhereonlyoneexcitedlevelhasbeendetermined
unambiguously is omitted.
Foreachnucleusalevel-andgamma-transitionscheme,andatablearepresented. Theschemes
and tables are ordered by atomic number (Z) and subordered by mass number (A). The table
contains the most important quantitative information on the level properties. The level scheme
gives mainly a general impression about the character of the nuclear spectrum and the electro-
magnetic transitions between the levels. As a rule only those levels are depicted in the scheme
of which decays by electromagnetic transitions have been experimentally observed. In this sense
information in the table is more complete than in the figure. In a few exceptional cases (e.g., in
112Cd or 143Nd) in which the number of well-established levels exceeds ≈ 70 and it is not possible
to presentallofthem in a figurefor technicalreasons,the higher-lyingpartofthe spectrumis not
depicted in the level scheme.
Both in the figures and tables each nuclear level is specified by the total angular momentum
J, parity π, and order index n = 1, 2, ..., which indicates whether a state with quantum numbers
Jπ is the first, second, etc., in the presented level scheme. In deformed nuclei the total angular
momentumisdesignatedasI inaccordancewiththeprescriptionsinthefollowingchaptersmainly
dealing with deformed nuclei.
Description of the level schemes
Energylevels are depicted by horizontallines, bold-typed lines correspondingto the groundstate.
On the right-hand side of the lines the level energies are marked, while the quantum numbers Jπ
n
(Iπ in deformed nuclei) are shown on the left-hand side. Vertical lines depict γ-transitions from
n
aninitial(upper)leveltoafinal(lower)level. Atthe finallevelthe lineoftransitionhasanarrow.
Thetransitionfromagivenlevelwiththelargestintensityisplottedbyathickline. Itispertinent
tonotethattransitionsofE0typearealsodepictedintheschemesbetweenlevelswithJπ =0+,in
whichnoelectromagneticradiationisemitted, buttheleveldischargeisaccomplishedbymeansof
conversionelectron release. Only those transitions are shown in the schemes for which conversion
electrons have been experimentally observed.
In deformed nuclei in addition to the ”complete” level scheme we present a figure with well-
establishedrotationalbandsandintra-bandγ-transitions. HereeachlevelischaracterizedexceptI
andπ by a quantum number K which is the projectionof the totalmomentum I onto the nuclear
symmetry axis. The sub-index n again discriminates states with the same Kπ in accordance
with increasing excitation energies. The ground state band of an even-even nucleus is denoted by
IπK =0+0 , 2+0 , 4+0 , etc. Excited states of a rotational band built on a lowest intrinsic
gsb gsb gsb
state with given Kπ are denoted by IπK , on the next state with the same Kπ – IπK , etc.
1 2
Atthebottomofthefigurevaluesofneutron,S ,andproton,S ,separationenergiesandmass
n p
excess ∆ for the ground state of the nucleus are provided in keV.
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Introduction XI
Description of the tables
As a rule here we follow the notation of the “Nuclear Data Sheets” and “Evaluated Nuclear
Structure Data Files”.
The levels are listed in the order of increasing energy. The rows contain experimental data on
properties of the ground state and excited states. The data include:
• Total angular momentum J (I in deformed nuclei) in units of h¯ and parity π of the state.
• Level energy E, in units of keV, is expressed in rounded numbers. Tenths of keV are given
only if necessary, e.g., to distinguish between two levels of the same energy if expressed in
round numbers of keV.
• Level half-life T1/2 in conventional units: y = year, ky = 103y, My = 106y, Gy = 109y,
Ty=1012y,Py=1015y,Ey=1018y,Zy=1021y,Yy=1024y,d=day,h=hour,m=minute,
s = second, ms = 10−3s, µs = 10−6s, ns = 10−9s, ps = 10−12s, fs = 10−15s.
• Reducedγ-transitionsprobabilitiesB(Eλ→Jπ)orB(Mλ→Jπ)fromthe givenlevelto the
f f
Jπ level, in Weiskopf‘s units:
f
(cid:1) (cid:2)
1 3 2
B(Eλ)W.u. = 4π λ+3 (1.2·A1/3)2λ e2 fm2λ ,
(cid:1) (cid:2)
10 3 2
B(Mλ)W.u. = π λ+3 (1.2·A1/3)2λ−2 µ2n fm2λ−2 .
For γ-transitions of mixed multipolarities (M1+E2), (E1+M2), etc., the designation, e.g.,
B(M1/E2→ Jπ) = a/b, δ = c, means that for the experimentally determined mixing ratio,
f
δ = c, the reduced probability of the M1-transition equals a, and that of the E2-transition
equals b; if for a given transition of mixed multipolarities only δ is measured the following
notation is used: M1/E2→Jπ :δ =c.
f
• Probabilities of β∓-, electron capture (EC)-transitions to the level, e.g.,
logft=a(β− fromJπ),whereJπ denotesspinandparityofthemothernucleuslevelsuffer-
ingβ-decay. Thefirst-forbiddenuniquetransitionsaredenotedaslogft = a1u(β− fromJπ)
and the second-forbidden unique transitions as logft = a2u (β− from Jπ).
• α-transition hindrance factor, HF = a (α from Jπ).
• Magnetic moment of the state, µ, in units of the nucleon magnetic moment µn.
• Quadrupole moment of the state, Q, in units of barn.
• A list of nuclear reactions in which the level was observed. Conventional designations of
these reactions are used: (γ,γ(cid:3)), (n,n’γ), (d,p), (α, xnγ), (HI, xnγ), etc.
Landolt-Bo¨rnstein
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Chapter 4
Energy and structure of levels of the isotopes with
Z = 37 to Z = 49
V.V. Voronov
Bogoliubov Laboratory of Theoretical Physics
Joint Institute for Nuclear Research
Dubna, Russia
83
4–2 Rb [Ref. p. 4–165
37 46
5/2+1 424
9/2+1 ? 42
3/2− 5
1 ?
5/2−1 ? ? ? 0
Jnπ Sn = 10913 keV, Sp = 5741 keV, ∆ = −79072.696keV E [keV]
Jnπ E T1/2 B(E(M)λ) and logft values, moments and main reactions
[keV] Refs. [92B3, 97A, 99B]
5/2−1 0 86.2 d logft=6.7 (β+ from 7/2+), µ=1.4249 µn, Q=0.196 barn,
(6Li,3nγ), (α,p), (p,γ)
3/2− 5 71.5 ns B(M1→5/2−)=0.200 W.u., (6Li,3nγ), (3He,d), (p,γ)
1 1
9/2+ 42 ≥0.3 ms logft=6.7 (β+ from 7/2+), (6Li,3nγ), (3He,d), (α,p), (p,γ)
1
5/2+ 424 74 ps B(E1→3/2−)=1.4×10−5 W.u., B(E1→5/2−)=5.0×10−6 W.u.,
1 1 1
B(E2→9/2+)=31 W.u., logft=6.4822 (β+ rom 7/2+),
1
(6Li,3nγ), (3He,d), (p,γ)
1/2+ 2691 (3He,d)
1
1/2+ 3059 (3He,d)
2
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84
Ref. p. 4–165] Rb 4–3
37 47
6− 464
1
3−
1 ? 248
2− 0
1 ? ?
Jnπ Sn = 8749 keV, Sp = 7057 keV, ∆ = −79750.149keV E [keV]
Jnπ E T1/2 B(E(M)λ) and logft values, moments and main reactions
[keV] Refs. [97T, 97A, 99B]
2−1 0 32.77 d µ=−1.324116µn, Q=−0.015 barn,
(p,d), (d,α), (α,nγ)
3− 248 0.31 ns B(E2/M1→2−)=86/<0.0005 W.u., (δ >3),
1 1
(p,d), (d,α), (α,nγ)
6− 464 20.26 m B(M3/E4→3−)=0.00075/73W.u., (δ =1.3),
1 1
B(E4→2−)=0.146 W.u.,
1
µ=0.2129331µn, Q=0.57 barn,
(p,d), (d,α), (α,nγ)
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85
4–4 Rb [Ref. p. 4–165
37 48
1/2−3 1792
3/2−3 1296
5/2+1 951
1/2−2 886
7/2−1 869
3/2−2 ? 732
9/2+1 ? ? 514
1/2−1 ? ? 281
3/2−1 ? ? ? ? ? ? ? ? 151
5/2−1 ? ? ? ? ? ? ? ? 0
Jnπ Sn = 10490 keV, Sp = 7022 keV, ∆ = −82167.687keV E [keV]
Jnπ E T1/2 B(E(M)λ) and logft values, moments and main reactions
[keV] Refs. [91S1, 97A, 99B]
5/2−1 0 stable logft=9.45 (β− from 9/2+), µ=1.357 µn, Q=−0.23 barn,
(7Li,4nγ),(12C,p2nγ),Coul. ex.,(p,γ),(3He,d),(n,n(cid:2)γ),(n,n(cid:2)),(t,α),
(d,3He)
3/2− 151 0.71 ns B(M1/E2→5/2−)=0.0085/2.33W.u., (δ =0.072),
1 1
logft=5.252 (β− from 1/2−), logft=4.53 (EC from (1/2)−),
(7Li,4nγ),(12C,p2nγ),Coul. ex.,(p,γ),(3He,d),(n,n(cid:2)γ),(n,n(cid:2)),(t,α),
(d,3He)
1/2− 281 40 ps B(M1→3/2−)=0.237 W.u., B(E2→5/2−)=2.14 W.u.,
1 1 1
logft=7.404 (β− from 1/2−), logft=6.41 (EC from (1/2)−),
(7Li,4nγ),(12C,p2nγ),Coul. ex.,(p,γ),(3He,d),(n,n(cid:2)γ),(n,n(cid:2)),(t,α),
(d,3He)
9/2+1 514 1.015 µs logft=9.51 (β− from 9/2+), µ=6.046 µn,
B(E3→3/2−)=0.0045W.u.,(7Li,4nγ),(12C,p2nγ),(3He,d),(n,n(cid:2)γ),
1
(n,n(cid:2)), (t,α), (d,3He)
3/2− 732 4.4 ps B(M1/E2→1/2−)=0.016/33W.u., (δ =−0.60),
2 1
B(M1/E2→3/2−)=0.00016/4.5W.u., (δ =0.62),
1
logft = 7.11 (β− from 1/2−), Coul. ex., (p,γ), (3He,d), (n,n(cid:2)γ),
(n,n(cid:2)), (t,α), (d,3He)
7/2− 869 2.5 ps B(E1→9/2+)=5.7×10−5 W.u., B(E2→1/2−)=0.47 W.u.,
1 1 1
B(M1/E2→5/2−)=0.0042/11.8W.u., (δ =1.10),
1
Coul. ex., (p,γ), (n,n(cid:2)γ), (n,n(cid:2))
1/2− 886 0.78 ps B(E2→ 5/2−) = 2.1 W.u., (p,γ), (3He,d), (n,n(cid:2)γ), (n,n(cid:2)), (t,α),
2 1
(d,3He)
5/2+ 951 2.8 ps B(E2→9/2+)=19 W.u., B(E1→3/2−)=2.3×10−5 W.u.,
1 1 1
B(E1→5/2−)=1.3×10−5W.u.,(7Li,4nγ),(12C,p2nγ),(p,γ),(p,p(cid:2)),
1
(3He,d), (n,n(cid:2)γ), (n,n(cid:2))
3/2− 1296 0.17 ps (p,γ), (3He,d), (n,n(cid:2)γ), (n,n(cid:2)), (t,α), (d,3He)
3
1/2− 1792 ≤ 0.12 ps (p,γ), (3He,d), (n,n(cid:2)γ), (n,n(cid:2)), (t,α), (d,3He)
3
1/2+ 2801 (3He,d)
1
1/2+ 2948 (3He,d)
2
1/2+ 3656 (3He,d)
3
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New Series I/18B
86
Ref. p. 4–165] Rb 4–5
37 49
1+ 2598
3
1+ 2093
2
3+ 1305
1
7− 780
1
6− 556
1 ?
1+ 488
1 ?
2− 0
1 ? ? ? ?
Jnπ Sn = 8651.0 keV, Sp = 8555.7 keV, ∆=−82747.319keV E [keV]
Jnπ E T1/2 B(E(M)λ) and logft values, moments and main reactions
[keV] Refs. [88M1, 97A, 99B]
2−1 0 18.631 d µ=−1.6920 µn, Q=0.193 barn,
(3He,p), (d,p), (n,γ), (d,t), (d,3He), (d,α), (p,nγ), (7Li,3nγ)
1+ 488 2.4 ps B(E1→2−)=0.0012 W.u.,
1 1
(3He,p), (d,p), (n,γ), (d,t), (3He,α), (d,α), (p,nγ)
6− 556 1.017 m B(E4→2−)=1.455 W.u.,
1 1
µ=1.8150 µn, Q=0.369 barn,
(d,p), (n,γ), (d,t), (3He,α), (d,3He), (d,α), (7Li,3nγ)
7− 780 (d,p), (n,γ), (d,3He), (d,α), (7Li,3nγ)
1
3+ 1305 (n,γ), (d,t), (d,α)
1
1+ 2093 (3He,p) (d,p)
2
1+ 2598 (3He,p), (n,γ), (d,α)
3
1+ 2951 (d,α)
4
1+ 3113 (3He,p)
5
1+ 3205 (3He,p)
6
1+ 3319 (3He,p) (d,α)
7
1+ 4221 (3He,p)
8
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New Series I/18B
87
4–6 Rb [Ref. p. 4–165
37 50
1/2+ 17193
15
7/2+1 16512
1/2+ 16040
14
1/2+13 14490
5/2+1 13968
1/2+12 6989
1/2+11 6838
1/2+10 6548
1/2+9 6468
1/2+8 6176
1/2+7 6018
1/2+6 5750
1/2+5 5634
1/2+4 5196
1/2+3 4941
1/2+ 3834
2
1/2+1 3060
5/2− 403
1
3/2−1 ? 0
Jnπ Sn = 9920.3 keV, Sp = 8620 keV, ∆ = −82606.221keV E [keV]
Jnπ E T1/2 B(E(M)λ) and logft values, moments and main reactions
[keV] Refs. [91S2, 97A, 99B]
3/2− 0 47.5 Gy logft=7.81 (β− from 5/2+), logft=4.4013 (EC from 1/2−),
1
µ=0.127µn,Q=2.751818barn,Coul. ex.,(3He,d),(n,n(cid:2)γ),(d,3He)
5/2− 403 0.08 ns B(M1/E2→3/2−)=0.004/1.63W.u., (δ =−0.24),
1 1
logft=7.47 (β− from 5/2+),
Coul. ex., (3He,d), (n,n(cid:2)γ), (p,p(cid:2)), (d,3He)
1/2+ 3060 (3He,d), (p,p(cid:2))
1
1/2+ 3834 (3He,d)
2
1/2+ 4941 (3He,d)
3
1/2+ 5196 (3He,d)
4
1/2+ 5634 (3He,d)
5
1/2+ 5750 (3He,d)
6
1/2+ 6018 (3He,d)
7
1/2+ 6176 (3He,d)
8
1/2+ 6468 (3He,d)
9
1/2+ 6548 (3He,d)
10
1/2+ 6838 (3He,d)
11
1/2+ 6989 (3He,d)
12
5/2+ 13968 (p,p(cid:2))
1
1/2+ 14490 (p,p(cid:2))
13
1/2+ 16040 (p,p(cid:2))
14
7/2+ 16512 (p,p(cid:2))
1
1/2+ 17193 (p,p(cid:2))
15
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New Series I/18B
82
Ref. p. 4–165] Sr 4–7
38 44
18+ 9238
1
17− 8842
1
16− 8378
1
16+ 7812
1 ?
15− 7546
1 ?
14− 7067
1 ?
14+ 6544
1 ?
13− 6367
1 ?
12− 5914
1 ?
12+ 5569
2
12+ 5427
1 ?
11− 5308
1 ?
10− 5237
2
10− 4909
1 ?
9+ 4493
1
9− 4473
2
9− 4367
1 ?
10+ 4350
1 ?
8− 4143
2 ?
8− 4033
1 ?
8+ 3623
2
7− 3608
3 ? ?
7− 3566
2 ?? ?
7− 3526
1 ?? ? ?
7+ 3477
1 ?
6− 3340
2 ?
8+ 3243
1 ? ? ?
6− 3086
1 ? ? ? ?
4− 3007
2 ?
6+ 2836
2 ? ?
4− 2824
1 ?
5− 2817
1 ? ? ? ? ?
0+ 2665
3
5+ 2526
1 ?? ?
3− 2402
1 ? ??
6+ 2229
1 ? ? ? ? ? ? ?
2+ 2195
4
4+ 1996
2 ?? ? ?
2+ 1865
3
3+ 1689
1 ? ? ? ?
4+ 1329
1 ? ? ?? ? ? ?
0+ 1311
2
2+ 1176
2 ? ?
2+ 574
1 ? ? ? ???
0+ 0
1 ??
Jnπ Sn = 12554 keV, Sp = 7840 keV, ∆=−76008.727keV E [keV]
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New Series I/18B