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Search: Author = H.Helppi

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1987HO15      Phys.Lett. 195B, 321 (1987)

R.Holzmann, I.Ahmad, B.K.Dichter, H.Emling, R.V.F.Janssens, T.L.Khoo, W.C.Ma, M.W.Drigert, U.Garg, D.C.Radford, P.J.Daly, Z.Grabowski, H.Helppi, M.Quader, W.Trzaska

Evolution of Nuclear Structure with Increasing Spin and Internal Excitation Energy in ¹⁵²Dy

NUCLEAR REACTIONS ⁷⁶Ge(⁸⁰Se, 4n), E=311 MeV; ¹²⁰Sn(³⁶S, 4n), E=157 MeV; measured Eγ, Iγ, total γ-spectrum. ¹⁵²Dy deduced average γ-multiplicities, γ-multipolarity, spectral shapes, decay path to isomer.

doi: 10.1016/0370-2693(87)90025-6
Citations: PlumX Metrics

1986GA21      Phys.Lett. 180B, 319 (1986)

U.Garg, A.Chaudhury, M.W.Drigert, E.G.Funk, J.W.Mihelich, D.C.Radford, H.Helppi, R.Holzmann, R.V.F.Janssens, T.L.Khoo, A.M.van den Berg, J.L.Wood

Lifetime Measurements in ¹⁸⁴Pt and the Shape Coexistence Picture

NUCLEAR REACTIONS ¹⁵⁴Sm(³⁴S, 4n), E=160 MeV; measured γ spectra, recoil distance. ¹⁸⁴Pt deduced levels, T_1/2, B(E2), shape coexistence. Recoil distance technique, enriched target.

doi: 10.1016/0370-2693(86)91195-0
Citations: PlumX Metrics

1986MC14      Z.Phys. A325, 27 (1986)

J.McNeill, R.Broda, Y.H.Chung, P.J.Daly, Z.W.Grabowski, H.Helppi, M.Kortelahti, R.V.F.Janssens, T.L.Khoo, R.D.Lawson, D.C.Radford, J.Blomqvist

Level Structure of Proton-Rich N = 83 Nuclei ¹⁵⁰Ho and ¹⁵²Tm

NUCLEAR REACTIONS ⁹²Zr, ⁹⁴Mo(⁶⁰Ni, np), ⁹³Nb(⁶⁰Ni, n2p), E=240-250 MeV; measured γγ-coin, sum spectra, γ(t). ¹⁵⁰Ho, ¹⁵²Tm deduced levels, J, π, isomer, T_1/2, decay characteristics, B(λ), γ-branching, γ-multipolarity, ICC. Enriched metallic targets, NaI sum spectrometer, Ge(Li) detectors. Shell model calculations.

1985BR07      Z.Phys. A321, 287 (1985)

R.Broda, P.J.Daly, Z.W.Grabowski, H.Helppi, M.Kortelahti, J.McNeill, R.V.F.Janssens, R.D.Lawson, D.C.Radford, J.Blomqvist

Two-Proton Neutron-Hole Yrast Excitations in ¹⁴⁷₆₆Dy₈₁

NUCLEAR REACTIONS ⁸⁹Y(⁶⁰Ni, np), ⁹⁰Zr(⁶⁰Ni, n2p), ⁹²Zr(⁵⁸Ni, n2p), E=230-250 MeV; measured Eγ, Iγ, γγ-coin. ¹⁴⁷Dy deduced levels, J, π, yrast sequence, γ-multipolarity, branching, transition widths, ICC, seniority characteristics, B(λ), configurations.

doi: 10.1007/BF01493450
Citations: PlumX Metrics

1985RA22      Phys.Rev.Lett. 55, 1727 (1985)

D.C.Radford, I.Ahmad, R.Holzmann, R.V.F.Janssens, T.L.Khoo, M.L.Drigert, U.Garg, H.Helppi

Total γ-Ray Spectrum in ¹⁵³Ho: From the yrast line into the continuum

NUCLEAR REACTIONS ¹²⁰Sn(³⁷Cl, 4n), E=165 MeV; measured Eγ, Iγ. ¹⁵³Ho deduced yrast, preyrast transitions, stretched transition multipole decomposition.

doi: 10.1103/PhysRevLett.55.1727
Citations: PlumX Metrics

1984CH11      Phys.Rev. C29, 2153 (1984)

Y.H.Chung, P.J.Daly, H.Helppi, R.Broda, Z.W.Grabowski, M.Kortelahti, J.McNeill, A.Pakkanen, P.Chowdhury, R.V.F.Janssens, T.L.Khoo, J.Blomqvist

Four-Valence-Proton Yrast States in ¹⁵⁰₆₈Er₈₂

NUCLEAR REACTIONS ^92,94Zr, ⁹³Nb, ^92,94,95Mo(⁵⁸Ni, xnyp), (⁶⁰Ni, xnyp), ⁹³Nb(⁶⁰Ni, 2np), ⁹⁵Mo(⁵⁸Ni, n2p), E=225-255 MeV; measured Eγ, Iγ, γγ(t), σ(Eγ, E), γγ-coin, X-rayγ-coin. ¹⁵⁰Er deduced levels, T_1/2, yrast sequence, isomers, ICC, γ-branching, J, π, B(E2), γ-multipolarity. Shell model.

doi: 10.1103/PhysRevC.29.2153
Citations: PlumX Metrics

1984LO12      ATOMKI Kozlem. 26, 29 (1984)

T.Lonnroth, J.Hattula, H.Helppi, S.Juutinen, K.Honkanen, A.Kerek

Study of Band Crossings in ¹³⁰Xe

NUCLEAR REACTIONS ¹³⁰Te(α, 4n), E not given; measured γ-spectra. ¹³⁰Xe deduced levels, J, π, band structure, γ-multipolarity. Triaxial cranking shell model. In-beam spectroscopy.

1984LO19      Nucl.Phys. A431, 256 (1984)

T.Lonnroth, J.Hattula, H.Helppi, S.Juutinen, K.Honkanen, A.Kerek

Study of Band Crossings in ¹³⁰Xe

NUCLEAR STRUCTURE ¹³⁰Xe; calculated levels, band structure; deduced quasiparticle content. Cranked shell model.

NUCLEAR REACTIONS ¹³⁰Te(α, 4n), E=42-51 MeV; measured γγ-coin, Iγ(E), γ(θ). ¹³⁰Xe deduced levels, J, π, band structure.

doi: 10.1016/0375-9474(84)90174-X
Citations: PlumX Metrics

1983HA30      Phys.Rev. C28, 1860 (1983)

J.Hattula, S.Juutinen, H.Helppi, A.Pakkanen, M.Piiparinen, S.Elfstrom, Th.Lindblad

Band Crossings in ⁸⁶Zr

NUCLEAR REACTIONS Sr(³He, xnγ), E=27 MeV; Sr(α, xnγ), E=55 MeV; measured Eγ, Iγ, γγ(t), γ(θ). ⁸⁶Zr deduced levels, T_1/2, band structure, yrast line backbending characteristics.

doi: 10.1103/PhysRevC.28.1860
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1983HE14      Phys.Rev. C28, 1382 (1983)

H.Helppi, S.K.Saha, P.J.Daly, S.R.Faber, T.L.Khoo

Rotation-Aligned Bands in ¹⁹⁶Hg

NUCLEAR REACTIONS ¹⁹⁶Pt(α, 4n), E=48.6 MeV; measured Eγ, Iγ(θ), γγ(t), γγ-coin. ¹⁹⁶Hg deduced high-spin levels, J, π, backbending, γ-branching. Cranked shell model.

doi: 10.1103/PhysRevC.28.1382
Citations: PlumX Metrics

1983KH03      Phys.Scr. T5, 16 (1983)

T.L.Khoo, P.Chowdhury, H.Emling, D.Frekers, R.V.F.Janssens, W.Kuhn, A.Pakkanen, Y.H.Chung, P.J.Daly, Z.W.Grabowski, H.Helppi, M.Kortelahti, S.Bjornholm, J.Borggreen, J.Pedersen, G.Sletten

Nuclear Shape Transitions and Some Properties of Aligned-Particle Configurations at High Spin

NUCLEAR STRUCTURE ^{148,152,156,160}Dy, ¹⁴⁷Gd; analyzed high-spin state, effective quadrupole moment, feeding times data; deduced shape dependence on spin, neutron number.

NUCLEAR REACTIONS ¹²²Sn(³⁰Si, 5n), E not given; measured γγ-coin. ¹⁴⁷Gd deduced levels, γ-branching.

doi: 10.1088/0031-8949/1983/T5/003
Citations: PlumX Metrics

1983KO45      Phys.Lett. 131B, 305 (1983)

M.Kortelahti, R.Broda, Y.H.Chung, P.J.Daly, H.Helppi, J.Mcneill, A.Pakkanen, P.Chowdhury, R.V.F.Janssens, T.L.Khoo, W.Kuhn

Level Structure of ¹⁵³Dy and the Competition between Collective and Few-Particle Excitation Modes in Dy Nuclei

NUCLEAR REACTIONS ¹²⁴Sn(³⁴S, 5n), E=145-165 MeV; measured γ(θ), σ(Eγ, E), γγ-coin, γγ(t). ¹⁵³Dy deduced levels, γ-branching, isomer configuration, J, π, B(E2), shape, collective, few particle excitation mode competitions.

doi: 10.1016/0370-2693(83)90504-X
Citations: PlumX Metrics

1982HA44      Phys.Scr. 26, 205 (1982)

J.Hattula, H.Helppi, A.Luukko

In-Beam Study of ^122,124,126Xe

NUCLEAR REACTIONS ^122,124,126Te(³He, 3n), E=20-27 MeV; measured Eγ, Iγ, I(ce), γ(θ), σ(Eγ) vs E, γγ-coin. ^122,124,126Xe deduced levels, J, π, ICC, δ, γ-branching, band structure. ¹²⁶Xe deduced isomer J, π, T_1/2.

doi: 10.1088/0031-8949/26/3/011
Citations: PlumX Metrics

1982HE08      Phys.Lett. 115B, 11 (1982)

H.Helppi, Y.H.Chung, P.J.Daly, S.R.Faber, A.Pakkanen, I.Ahmad, P.Chowdhury, Z.W.Grabowski, T.L.Khoo, R.D.Lawson, J.Blomqvist

Yrast (πh_11/2)(n) Excitations in Proton-Rich N = 82 Nuclei

NUCLEAR REACTIONS ^92,94Zr, ⁹³Nb, ^92,94,95Mo(⁵⁸Ni, X), (⁶²Ni, X), E=225-285 MeV; measured σ(Eγ), γγ-, γ(X-ray)-coin. ¹⁵⁰Er, ¹⁵¹Tm deduced levels, γ-branching, J, π, isomer T_1/2, B(λ), configuration.

doi: 10.1016/0370-2693(82)90504-4
Citations: PlumX Metrics

1982PA10      Phys.Rev.Lett. 48, 1530 (1982)

A.Pakkanen, Y.H.Chung, P.J.Daly, S.R.Faber, H.Helppi, J.Wilson, P.Chowdhury, T.L.Khoo, I.Ahmad, J.Borggreen, Z.W.Grabowski, D.C.Radford

Transition from Collective to Aligned-Particle Configurations at High Spin in ¹⁵⁴Dy

NUCLEAR REACTIONS ¹²⁴Sn(³⁴S, 4n), E=145-165 MeV; measured γγ-coin, γ(θ), σ(Eγ), recoil. ¹⁵⁴Dy deduced levels, J, π, γ-branching, T_1/2, yrast level intrinsic quadrupole moments, backbending, shape change.

doi: 10.1103/PhysRevLett.48.1530
Citations: PlumX Metrics

1981DO05      J.Phys.(London) G7, 1379 (1981)

F.Donau, J.Hattula, H.Helppi, A.Luukko, M.Jaaskelainen

How to Describe Low-Lying Bands in Odd-A Transitional Xenon Nuclei

NUCLEAR STRUCTURE ^{123,125,127,129}Xe; calculated levels, band structure. Core-quasiparticle model.

doi: 10.1088/0305-4616/7/10/015
Citations: PlumX Metrics

1981GO04      Nucl.Phys. A357, 109 (1981)

L.Goettig, Ch.Droste, A.Dygo, T.Morek, J.Srebrny, R.Broda, J.Styczen, J.Hattula, H.Helppi, M.Jaaskelainen

In-Beam Study of the ^128,130Xe Nuclei

NUCLEAR REACTIONS ^126,128Te(α, 2nγ), E=25.5-27 MeV; ^128,130Te(³He, 3nγ), E=20-27 MeV; measured Eγ, Iγ(θ), I(ce), γγ(t), αγ(t), ³Heγ(t), σ(Eγ). ^128,130Xe deduced levels, J, π, T_1/2, γ-multipolarity, δ, ICC.

doi: 10.1016/0375-9474(81)90628-X
Citations: PlumX Metrics

1981HE04      Nucl.Phys. A357, 333 (1981)

H.Helppi, J.Hattula, A.Luukko, M.Jaaskelainen, F.Donau

In-Beam Study of ^127,129Xe and Collective Description of the Level Structures in Odd-A Xe Nuclei

NUCLEAR REACTIONS ¹²⁶Te(³He, 2n), ^128,130Te(³He, 4n), E=20-27 MeV; ¹²⁶Te(α, n), E=18 MeV; measured Eγ, Iγ(θ), γγ-coin, γ(t), I(ce). ^127,129Xe deduced levels, J, π, T_1/2, ICC, δ(E2/M1). Enriched targets.

NUCLEAR STRUCTURE ^{123,125,127,129}Xe; calculated levels, band structure. Triaxial rotor, core plus quasiparticle model calculations.

doi: 10.1016/0375-9474(81)90225-6
Citations: PlumX Metrics

1981HE07      Phys.Rev. C23, 1446 (1981)

H.Helppi, S.K.Saha, P.J.Daly, S.R.Faber, T.L.Khoo, F.M.Bernthal

High-Spin Level Spectra of the Nuclei ¹⁹⁵Pb, ¹⁹⁷Pb, ¹⁹⁹Pb, and ²⁰¹Pb

NUCLEAR REACTIONS ^200,198Hg(α, 3n), E=35-45 MeV; ¹⁹⁸Hg(³He, 4n), E=38 MeV; ¹⁹⁸Hg(³He, 6n), ¹⁹⁹Hg(³He, 7n), E=74 MeV; measured Eγ, Iγ(θ), γγ-coin, γγ(t). ^{195,197,199,201}Pb deduced high-spin levels, J, π, T_1/2.

doi: 10.1103/PhysRevC.23.1446
Citations: PlumX Metrics

1981HE10      Phys.Rev. C23, 2345 (1981)

H.Helppi, S.K.Saha, M.Piiparinen, C.L.Dors, P.J.Daly, T.L.Khoo

High-Spin Level Structure of ²⁰⁰Hg

NUCLEAR REACTIONS ¹⁹⁸Pt(α, 2n), E=26-28 MeV; measured Eγ, Iγ(θ), γγ-coin. ²⁰⁰Hg deduced high-spin levels, J, π, γ-multipolarity.

doi: 10.1103/PhysRevC.23.2345
Citations: PlumX Metrics

1981LU01      Nucl.Phys. A357, 319 (1981)

A.Luukko, J.Hattula, H.Helppi, O.Knuuttila, F.Donau

Level Structure in ¹²³Xe

NUCLEAR REACTIONS ¹²²Te(³He, 2n), ¹²³Te(³He, 3n), E=14-27 MeV; measured Eγ, Iγ(θ), γγ-coin, γ(t), I(ce). ¹²³Xe deduced levels, J, π, T_1/2, ICC, δ(E2/M1). Enriched targets.

doi: 10.1016/0375-9474(81)90224-4
Citations: PlumX Metrics

1979HE15      Nucl.Phys. A332, 183 (1979)

H.Helppi, J.Hattula, A.Luukko

Even- and Odd-Parity Band Structures in ¹²⁵Xe

NUCLEAR REACTIONS ¹²⁵Te(³He, 3nγ), E=20-27 MeV; measured Eγ, Iγ(θ), γγ-coin, γ(t). ¹²⁵Xe deduced levels, J, π, T_1/2. Enriched target.

doi: 10.1016/0375-9474(79)90103-9
Citations: PlumX Metrics

1977HE06      Phys.Lett. 67B, 279 (1977)

H.Helppi, S.K.Saha, P.J.Daly, S.R.Faber, T.L.Khoo, F.M.Bernthal

High-Spin Neutron Hole Excitations in Light Odd-A Pb Nuclei

NUCLEAR REACTIONS ^198,200,202Hg(α, 3nγ), (³He, xnγ), E=not given; measured σ(E), Eγ, Iγ, γγ(t). ^{195,197,199,201,203}Pb deduced levels, T_1/2, J, π.

doi: 10.1016/0370-2693(77)90370-7
Citations: PlumX Metrics

1977SA18      Phys.Rev. C16, 2159 (1977)

S.K.Saha, H.Helppi, P.J.Daly, S.R.Faber, T.L.Khoo, F.M.Bernthal

High-Spin Level Structure of the Five Neutron Hole Nucleus ²⁰³Pb

NUCLEAR REACTIONS ²⁰²Hg(α, 3nγ), E=38.2 MeV; measured Eγ, Iγ, γγ-coin, γ(θ, t). ²⁰³Pb deduced levels, J, π, T_1/2.

doi: 10.1103/PhysRevC.16.2159
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1975HE13      Nucl.Phys. A247, 317 (1975)

H.Helppi, A.Pakkanen, J.Hattula

Mixing of the Transitions from the 3⁺ Quasi γ-Band Level in ¹⁵²Gd

RADIOACTIVITY ¹⁵²Eu [from ¹⁵¹Eu(n, γ)]; measured γγ(θ). ¹⁵²Gd deduced B(E2) ratios, γ-multipole mixing. Enriched target.

doi: 10.1016/0375-9474(75)90638-7
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1975PA07      Z.Phys. A274, 127 (1975)

A.Pakkanen, M.Kortelahti, H.Helppi, J.Kantele, T.Poikolainen, R.Komu

Decay of 14.6 h ⁹⁰Nb

RADIOACTIVITY ⁹⁰Nb [from ⁹⁰Zr(p, n)]; measured Eγ, Iγ, γγ-coin; deduced log ft. ⁹⁰Zr deduced levels, J, π, γ-branching. Ge(Li), anti-Compton detectors. Natural targets.

doi: 10.1007/BF01408464
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1974HE08      Nucl.Phys. A223, 13 (1974)

H.Helppi, A.Pakkanen, J.Hattula

The E2/M1 Mixing of the Transitions from the Kπ = 2⁺ Bands in ^190,192Os and ¹⁹²Pt

RADIOACTIVITY ¹⁹⁰Ir [from ¹⁹²Os(p, 3n)], ¹⁹²Ir [from ¹⁹¹Ir(n, γ)]; measured γγ, γγ(θ). ^190,192Os, ¹⁹²Pt deduced γ-multipole mixing. Natural targets.

doi: 10.1016/0375-9474(74)90276-0
Citations: PlumX Metrics

1973PA08      Nucl.Phys. A206, 164 (1973)

A.Pakkanen, P.Puumalainen, H.Helppi, T.Komppa

Isomeric Transition in ¹⁹⁸Au

RADIOACTIVITY ^198mAu [from ¹⁹⁷Au(d, p), ¹⁹⁸Hg(n, p)]; measured T_1/2, Eγ, ICC, Iγ, I(ce), γγ-, ceγ-coin, γγ-delay, ICC; ¹⁹⁸Au deduced levels, J, π, T_1/2.

doi: 10.1016/0375-9474(73)90613-1
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1972HE36      Z.Phys. 255, 385 (1972)

H.Helppi, A.Pakkanen

Note on the Decay of ²⁰⁰Au

RADIOACTIVITY ²⁰⁰Au; measured Eγ, Iγ, Eβ, βγ-, γγ-coin; deduced log ft, Q. ²⁰⁰Hg deduced levels, J, π, γ-branching. Ge(Li), plastic detectors.

doi: 10.1007/BF01392472
Citations: PlumX Metrics

1972PA06      Nucl.Phys. A184, 157 (1972)

A.Pakkanen, T.Komppa, H.Helppi

New ²⁰⁴Au Activity and the Decay of ²⁰²Au

RADIOACTIVITY ²⁰²Au[from ²⁰²Hg(n, p), ²⁰⁵Tl(n, α)], ²⁰⁴Au[from ²⁰⁴Hg(n, p)]; measured T_1/2, Eγ, Iγ, γγ, γβ-coin; deduced log ft. ^202,204Hg deduced levels, J, π, γ-branching. Natural targets.

doi: 10.1016/0375-9474(72)90450-2
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1972PA24      Z.Phys. 254, 98 (1972)

A.Pakkanen, H.Helppi, T.Komppa, P.Puumalainen

Low-Lying Levels of ²⁰¹Hg from the Decay of ²⁰¹Au

RADIOACTIVITY ²⁰¹Au; measured Eγ, Iγ, γγ-coin, Eβ, βγ-coin, Xγ-coin; deduced Q, log ft. ²⁰¹Hg deduced levels, J, π, γ-branching. Ge(Li), Si(Li), NaI(Tl) detectors.

doi: 10.1007/BF01380058
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1972PA38      Comment.Phys.-Math. 42, 267 (1972)

A.Pakkanen, T.Komppa, H.Helppi

On Low-Lying Levels in Stable Even Mercury Isotopes

RADIOACTIVITY ^202,204Au; measured T_1/2. ^202,204Hg deduced levels.

1971HA09      Z.Phys. 241, 117 (1971)

J.Hattula, H.Helppi, J.Kantele

Directional Correlations of Some γ-Ray Cascades in ²⁰⁰Hg

RADIOACTIVITY ²⁰⁰Tl; measured γγ(θ). ²⁰⁰Hg levels deduced γ-mixing, J, π.

doi: 10.1007/BF01397900
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1970HE29      Phys.Scr. 2, 155 (1970)

H.Helppi, J.Hattula

Multipole Character of Some Gamma Transitions in ¹⁵²Sm

RADIOACTIVITY ¹⁵²Eu; measured γγ(θ). ¹⁵²Sm levels deduced J, π, γ-mixing. Ge(Li), NaI(Tl) detectors.

doi: 10.1088/0031-8949/2/4-5/005
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