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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, T1/2, 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, T1/2, 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, T1/2, 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, T1/2, band structure, yrast line backbending characteristics.

doi: 10.1103/PhysRevC.28.1860
Citations: PlumX Metrics


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
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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 148,152,156,160Dy, 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, T1/2.

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 (πh11/2)(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 T1/2, 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, T1/2, 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 123,125,127,129Xe; 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, T1/2, 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, T1/2, ICC, δ(E2/M1). Enriched targets.

NUCLEAR STRUCTURE 123,125,127,129Xe; 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). 195,197,199,201Pb deduced high-spin levels, J, π, T1/2.

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, T1/2, 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, T1/2. 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). 195,197,199,201,203Pb deduced levels, T1/2, 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, T1/2.

doi: 10.1103/PhysRevC.16.2159
Citations: PlumX Metrics


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
Citations: PlumX Metrics


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
Citations: PlumX Metrics


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 T1/2, Eγ, ICC, Iγ, I(ce), γγ-, ceγ-coin, γγ-delay, ICC; 198Au deduced levels, J, π, T1/2.

doi: 10.1016/0375-9474(73)90613-1
Citations: PlumX Metrics


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 T1/2, 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
Citations: PlumX Metrics


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
Citations: PlumX Metrics


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 T1/2. 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
Citations: PlumX Metrics


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
Citations: PlumX Metrics


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