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NSR database version of April 11, 2024.

Search: Author = D.E.Roa

Found 9 matches.

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1999AH07      Phys.Rev. C60, 064601 (1999)

I.Ahmad, S.M.Austin, B.B.Back, R.R.Betts, F.P.Calaprice, K.C.Chan, A.Chishti, C.M.Conner, R.W.Dunford, J.D.Fox, S.J.Freedman, M.Freer, S.B.Gazes, A.L.Hallin, Th.Happ, D.Henderson, N.I.Kaloskamis, E.Kashy, W.Kutschera, J.Last, C.J.Lister, M.Liu, M.R.Maier, D.M.Mercer, D.Mikolas, P.A.A.Perera, M.D.Rhein, D.E.Roa, J.P.Schiffer, T.A.Trainor, P.Wilt, J.S.Winfield, M.Wolanski, F.L.H.Wolfs, A.H.Wuosmaa, A.R.Young, J.E.Yurkon

Positron-Electron Pairs Produced in Heavy-Ion Collisions

NUCLEAR REACTIONS 232Th(238U, X), E=5.95 MeV/nucleon; 181Ta(238U, X), E=5.95, 6.1, 6.3 MeV/nucleon; measured positron, electron spectra, multiplicities, e-e+-coin, angular correlation; deduced no sharp structure in sum-energy spectra. APEX spectrometer.

doi: 10.1103/PhysRevC.60.064601
Citations: PlumX Metrics


1998WU02      Phys.Rev. C57, R2794 (1998)

A.H.Wuosmaa, C.M.Conner, I.Ahmad, B.B.Back, R.R.Betts, R.W.Dunford, S.M.Fischer, R.Ganz, J.P.Greene, N.I.Kaloskamis, L.Lamm, C.J.Lister, V.Nanal, D.E.Roa, J.P.Schiffer

Positron-Electron Angular Correlations in Internal Pair Conversion

RADIOACTIVITY 90Y(β-); 206,207Bi(EC); measured e+e--coin, sum energy spectra, opening angle correlations from internal pair conversion in daughter nuclei. 90Zr, 206,207Pb deduced transitions internal pair conversion coefficients.

doi: 10.1103/PhysRevC.57.R2794
Citations: PlumX Metrics


1997AH01      Phys.Rev.Lett. 78, 618 (1997)

I.Ahmad, S.M.Austin, B.B.Back, R.R.Betts, F.P.Calaprice, K.C.Chan, A.Chishti, C.Conner, R.W.Dunford, J.D.Fox, S.J.Freedman, M.Freer, S.B.Gazes, A.L.Hallin, T.Happ, D.Henderson, N.I.Kaloskamis, E.Kashy, W.Kutschera, J.Last, C.J.Lister, M.Liu, M.R.Maier, D.J.Mercer, D.Mikolas, P.A.A.Perera, M.D.Rhein, D.E.Roa, J.P.Schiffer, T.A.Trainor, P.Wilt, J.S.Winfield, M.R.Wolanski, F.L.H.Wolfs, A.H.Wuosmaa, G.Xu, A.Young, J.E.Yurkon, and the APEX Collaboration

Search for Monoenergetic Positron Emission from Heavy-Ion Collisions at Coulomb-Barrier Energies

NUCLEAR REACTIONS 181Ta(238U, X), E=5.95-6.3 MeV/nucleon; 232Th(238U, X), E=5.95 MeV/nucleon; measured positron energy spectra; deduced no structure.

doi: 10.1103/PhysRevLett.78.618
Citations: PlumX Metrics


1997AH04      Phys.Rev. C55, R2755 (1997)

I.Ahmad, S.M.Austin, B.B.Back, R.R.Betts, F.P.Calaprice, K.C.Chan, A.A.Chishti, C.Conner, R.W.Dunford, J.D.Fox, S.J.Freedman, M.Freer, J.S.Greenberg, S.B.Gazes, A.L.Hallin, T.Happ, D.Henderson, N.I.Kaloskamis, E.Kashy, W.Kutschera, J.Last, C.J.Lister, M.Liu, M.R.Maier, D.J.Mercer, D.Mikolas, P.A.A.Perera, M.D.Rhein, D.E.Roa, J.P.Schiffer, T.A.Trainor, P.Wilt, J.S.Winfield, M.Wolanski, F.L.H.Wolfs, A.H.Wuosmaa, G.Xu, A.Young, J.E.Yurkon, and the APEX Collaboration

Internal Pair Conversion in Heavy Nuclei

NUCLEAR REACTIONS 206Pb(206Pb, X), E=5.90 MeV/nucleon; measured e+e--sum energy spectra, Doppler corrected Eγ; deduced internal pair conversion to gamma branching ratio. 232Th(208Pb, X), E=5.80 MeV/nucleon; 238U(208Pb, X), E=5.80 MeV/nucleon; 181Ta(238U, X), E=5.95 MeV/nucleon; 232Th(238U, X), E=5.90 MeV/nucleon; measured e+e--sum energy, Doppler corrected Eγ; deduced no discrete lines evidence in e+e- spectra. 238U deduced new levels evidence.

doi: 10.1103/PhysRevC.55.R2755
Citations: PlumX Metrics


1997AH05      Z.Phys. A358, 235 (1997)

I.Ahmad, S.M.Austin, B.B.Back, R.R.Betts, F.P.Calaprice, K.C.Chan, A.Chishti, P.Chowdhury, C.Conner, R.W.Dunford, J.D.Fox, S.J.Freedman, M.Freer, S.B.Gazes, A.L.Hallin, T.Happ, D.Henderson, N.I.Kaloskamis, E.Kashy, W.Kutschera, J.Last, C.J.Lister, M.Liu, M.R.Maier, D.J.Mercer, D.Mikolas, P.A.A.Perera, M.D.Rhein, D.E.Roa, J.P.Schiffer, T.A.Trainor, P.Wilt, J.S.Winfield, M.Wolanski, F.L.H.Wolfs, A.H.Wuosmaa, A.Young, J.E.Yurkon, and the APEX Collaboration

The Positron-Electron Peak Puzzle: Results from APEX

NUCLEAR REACTIONS 232Th(238U, X), E=5.78-5.95 MeV/nucleon; 181Ta(238U, X), E=5.79-6.3 MeV/nucleon; measured total (e+)(heavy-ion)-, (e+e-)(heavy-ion)-coin events number; deduced very low light neutral particle production upper limits.

doi: 10.1007/s002180050316
Citations: PlumX Metrics


1996AH05      Acta Phys.Pol. B27, 387 (1996)

I.Ahmad, S.M.Austin, B.B.Back, R.R.Betts, F.P.Calaprice, K.C.Chan, A.Chishti, P.Chowdhury, C.Conner, R.W.Dunford, J.D.Fox, S.J.Freedman, M.Freer, S.Gazes, A.L.Hallin, T.Happ, N.Kaloskamis, E.Kashy, W.Kutschera, J.Last, C.J.Lister, M.Liu, M.R.Maier, D.J.Mercer, D.Mikolas, A.Perera, M.D.Rhein, D.E.Roa, J.P.Schiffer, T.Trainor, P.Wilt, J.S.Winfield, M.Wolanski, F.L.H.Wolfs, A.H.Wuosmaa, A.Young, J.E.Yurkon, and the APEX Collaboration

The Positron Peak Puzzle - Recent Results from APEX

NUCLEAR REACTIONS 232Th(238U, X), E=5.95 MeV/nucleon; 181Ta(238U, X), E=5.96-6.3 MeV/nucleon; 206Pb(206Pb, X), E not given; analyzed e+e--sum energy spectra. 232Th, 238U(208Pb, X), E=5.8 MeV/nucleon; 232Th, 181Ta(238U, X), E=5.95 MeV/nucleon; 206Pb(206Pb, X), E=5.9 MeV/nucleon; analyzed Doppler reconstructed γ spectra; deduced limits on 1.78 MeV 238U transition possible contribution to (heavy ion)γ-coin.


1996AH07      Nucl.Instrum.Methods Phys.Res. A370, 539 (1996)

I.Ahmad, S.M.Austin, B.B.Back, R.R.Betts, F.P.Calaprice, K.C.Chan, A.Chishti, P.Chowdhury, C.Conner, R.W.Dunford, J.D.Fox, S.J.Freedman, M.Freer, S.B.Gazes, J.S.Greenberg, J.P.Greene, A.L.Hallin, Th.Happ, D.Henderson, N.I.Kaloskamis, E.Kashy, W.Kutschera, J.Last, C.J.Lister, M.Liu, M.R.Maier, D.M.Mercer, D.Mikolas, P.A.A.Perera, M.D.Rhein, D.E.Roa, J.P.Schiffer, T.A.Trainor, P.Wilt, J.S.Winfield, M.Wolanski, F.L.H.Wolfs, A.H.Wuosmaa, G.Xu, A.R.Young, J.E.Yurkon

A Solenoidal Spectrometer for Positron-Electron Pairs Produced in Heavy-Ion Collisions

RADIOACTIVITY 85Sr(EC); 113Sn(EC); 203Hg(β-); measured electron spectra; deduced apparatus response, efficiency. New solenoidal spectrometer.

NUCLEAR REACTIONS 181Ta(238U, X), E=6.1 MeV/nucleon; measured γ-, positron energy spectra. New solenoidal spectrometer.

doi: 10.1016/0168-9002(95)00829-2
Citations: PlumX Metrics


1995AH01      Nucl.Phys. A583, 247c (1995)

I.Ahmad, S.M.Austin, B.B.Back, D.Bazin, R.R.Betts, F.P.Calaprice, K.C.Chan, A.Chishti, P.Chowdhury, R.W.Dunford, J.D.Fox, S.J.Freedman, M.Freer, S.B.Gazes, J.S.Greenberg, A.L.Hallin, T.Happ, J.Last, N.Kaloskamis, E.Kashy, W.Kutschera, C.J.Lister, M.Liu, M.R.Maier, D.Mercer, A.Perera, M.D.Rhein, D.E.Roa, J.P.Schiffer, T.Trainor, P.Wilt, J.S.Winfield, M.Wolanski, F.L.H.Wolfs, A.H.Wuosmaa, G.Xu, A.Young, J.E.Yurkon

Positron Production in Heavy Ion Collisions: Current status of the problem

NUCLEAR REACTIONS 181Ta(238U, X), E=5.9-6.3 MeV/nucleon; compiled, analyzed, reviewed electron, positron production data.

doi: 10.1016/0375-9474(94)00667-C
Citations: PlumX Metrics


1995AH06      Phys.Rev.Lett. 75, 2658 (1995)

I.Ahmad, S.M.Austin, B.B.Back, R.R.Betts, F.P.Calaprice, K.C.Chan, A.Chishti, P.Chowdhury, C.Conner, R.W.Dunford, J.D.Fox, S.J.Freedman, M.Freer, S.B.Gazes, A.L.Hallin, T.Happ, D.Henderson, N.I.Kaloskamis, E.Kashy, W.Kutschera, J.Last, C.J.Lister, M.Liu, M.R.Maier, D.J.Mercer, D.Mikolas, P.A.A.Perera, M.D.Rhein, D.E.Roa, J.P.Schiffer, T.A.Trainor, P.Wilt, J.S.Winfield, M.Wolanski, F.L.H.Wolfs, A.H.Wuosmaa, G.Xu, A.Young, J.E.Yurkon, and the APEX Collaboration

Search for Narrow Sum-Energy Lines in Electron-Positron Pair Emission from Heavy-Ion Collisions Near the Coulomb Barrier

NUCLEAR REACTIONS 181Ta(238U, X), E=5.95-6.3 MeV/nucleon; 232Th(238U, X), E=5.95 MeV/nucleon; measured pair emission sum spectra; deduced no sharp lines evidence, neutral particle isolated decay related features.

doi: 10.1103/PhysRevLett.75.2658
Citations: PlumX Metrics


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