A H Wuosmaa

Publications (157)221.43 Total impact

• Article: Neutron single-particle strength outside the N=50 core

  D K Sharp, B P Kay, J S Thomas, S J Freeman, J P Schiffer, B B Back, S Bedoor, T Bloxham, J A Clark, C M Deibel, C R Hoffman, A M Howard, J C Lighthall, S T Marley, A J Mitchell, T Otsuka, P D Parker, K E Rehm, D V Shetty, A H Wuosmaa
  Physical Review C 01/2013; 87(1):014312. · 3.31 Impact Factor
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  Available from: L. V. Grigorenko

  Article: Democratic Decay of ^{6}Be Exposed by Correlations.

  I A Egorova, R J Charity, L V Grigorenko, Z Chajecki, D Coupland, J M Elson, T K Ghosh, M E Howard, H Iwasaki, M Kilburn, [......], S T Marley, A Sanetullaev, R Shane, D V Shetty, L G Sobotka, M B Tsang, J Winkelbauer, A H Wuosmaa, M Youngs, M V Zhukov
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  ABSTRACT: The interaction of an E/A=70-MeV ^{7}Be beam with a Be target was used to populate levels in ^{6}Be following neutron knockout reactions. The three-body decay of the ground and first excited states into the α+p+p exit channel were detected in the High Resolution Array. Precise three-body correlations extracted from the experimental data allowed us to obtain insight into the mechanism of the three-body democratic decay. The correlation data are in good agreement with a three-cluster-model calculation and thus validate this theoretical approach over a broad energy range.
  Physical Review Letters 11/2012; 109(20):202502. · 7.37 Impact Factor
• Article: Democratic decay of 6Be exposed by correlations

  I. A. Egorova, R. J. Charity, L. V. Grigorenko, Z. Chajecki, D. Coupland, J. M. Elson, T. K. Ghosh, M. E. Howard, H. Iwasaki, M. Kilburn, [......], S. T. Marley, A. Sanetullaev, R. Shane, D. V. Shetty, L. G. Sobotka, M. B. Tsang, J. Winkelbauer, A. H. Wuosmaa, M. Youngs, M. V. Zhukov
  [show abstract] [hide abstract]
  ABSTRACT: The interaction of an E/A=70 - MeV 7Be beam with a Be target was used to populate levels in 6Be following neutron knockout reactions. The three-body decay of the ground and first excited states into the alpha+p+p exit channel were detected in the High Resolution Array. Precise three-body correlations extracted from the experimental data allowed us to obtain insight into the mechanism of the three-body democratic decay. The correlation data are in a good agreement with a three-cluster-model calculation and thus validate this theoretical approach over a broad energy range.
  08/2012;
• Article: Experimental study of the 19O(d, p)20O reaction in inverse kinematics

  C. R. Hoffman, B. B. Back, B. P. Kay, J. P. Schiffer, M. Alcorta, S. I. Baker, S. Bedoor, P. F. Bertone, J. A. Clark, C. M. Deibel, [......], S. T. Marley, R. C. Pardo, K. E. Rehm, A. Rojas, D. Santiago-Gonzalez, D. K. Sharp, D. V. Shetty, J. S. Thomas, I. Wiedenhöver, A. H. Wuosmaa
  [show abstract] [hide abstract]
  ABSTRACT: The neutron-adding (d,p) reaction was carried out in inverse kinematics to investigate the single-neutron overlap with the 19O ground state. Eight states in 20O were populated with measurable strength and a Q-value resolution of approximately 175 keV FWHM was achieved. Cross sections, angular distributions, spectroscopic factors, and T=1 diagonal two-body matrix elements were deduced. Results are discussed in terms of shell-model calculations confined to the 0d5/2, 1s1/2, and 0d3/2 orbitals.
  Phys. Rev. C. 05/2012; 85(5).
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  Available from: S. G. Steadman

  Article: PHOBOS at RHIC: Some global observations

  Alan S. Carroll, For the PHOBOS Collaboration, B. B. Back, M. D. Baker, D. S. Barton, R. R. Betts, M. Ballintijn, A. A. Bickley, R. Bindel, A. Budzanowski, [......], A. Trzupek, C. Vale, G. J. van Nieuwenhuizen, R. Verdier, B. Wadsworth, F. L. H. Wolfs, B. Wosiek, K. Woźniak, A. H. Wuosmaa, B. Wysłouch
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  ABSTRACT: Particle production in Au+Au collisions has been measured in the PHOBOS experiment at RHIC for a range of collision energies for a large span of pseudorapidities, |η| < 5.4. Three empirical observations have emerged from this data set which require theoretical examination. First, there is clear evidence of limiting fragmentation. Namely, particle production in central Au + Au collisions, when expressed as dN/dη′ ( η′ ≡ – ybeam), becomes energy independent at high energy for a broad region of η′ around η′ = 0. This energy-independent region grows with energy, allowing only a limited region (if any) of longitudinal boost-invariance. Second, there is a striking similarity between particle production in e+e−and Au + Au collisions (scaled by the number of participating nucleon pairs). Both the total number of produced particles and the longitudinal distribution of produced particles are approximately the same in e+e−and in scaled Au + Au. This observation This presentation is based in large part on the PHOBOS summary talk by M Baker at the16th Int. Conf. on Ultrarelativistic Nucleus- Nucleus Collisions, Quark Matter 2002, Nantes, France was not predicted and has not been explained. Finally, particle production has been found to scale approximately with the number of participating nucleon pairs for (N part ) > 65. This scaling occurs both for the total multiplicity and for highp T particles (3 <p T < 4.5 GeV/c).
  Pramana 04/2012; 61(5):865-876. · 0.57 Impact Factor
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  Available from: S. G. Steadman

  Article: A first look at Au+Au collisions at RHIC energies using the PHOBOS detector

  Birger Back, M. D. Baker, D. S. Barton, R. R. Betts, R. Bindel, A. Budzanowski, W. Busza, A. Carroll, J. Corbo, M. P. Decowski, [......], A. Trzupek, C. Vale, G. J. van Nieuwenhuizen, R. Verdier, B. Wadsworth, F. L. H. Wolfs, B. Wosiek, K. Woźniak, A. H. Wuosmaa, B. Wyslouch
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  ABSTRACT: The PHOBOS detector has been used to study Au + Au collisions at√sNN = 56,130, and 200 GeV Several global observables have been measured and the results are compared with theoretical models. These observables include the charged-particle multiplicity measured as a function of beam energy, pseudo-rapidity, and centrality of the collision. A unique feature of the PHOBOS detector is its almost complete angular coverage such that these quantities can be studied over a pseudo-rapidity interval of |η|≤5.4. This allows for an almost complete integration of the total charged particle yield, which is found to be about N ch tot = 4200 ±470 at √sNN = 130 GeV and N ch tot = 5300 ±530 at √sNN = 200 GeV. The ratio of anti-particles to particles emitted in the mid-rapidity region has also been measured using the PHOBOS magnetic spectrometer. Of particular interest is the ratio of anti-protons to protons in the mid-rapidity region, which was found to be (i.e.921-1) at √sNN = 130 GeV. This high value suggests that an almost baryon-free region has been produced in the collisions.
  Pramana 04/2012; 60(5):921-931. · 0.57 Impact Factor
• Conference Proceeding: Fusion reactions with the halo nucleus 15C

  M Alcorta, K E Rehm, B B Back, P F Bertone, B DiGiovine, H Esbensen, J P Greene, C R Hoffman, C L Jiang, R C Pardo, A M Rogers, S Bedoor, A H Wuosmaa, C M Deibel, J C Lighthall, S T Marley, M Paul, C Ugalde
  Bulletin of the American Physical Society; 10/2011
• Conference Proceeding: Recent results from HELIOS

  B B Back, B J DiGiovine, S Heimsath, A M James, C R Hoffman, B P Kay, A M Rogers, J P Schiffer, A H Wuosmaa, J C Lighthall, S T Marley
  5$^mathrmth$ International Conference FUSION11; 10/2011
• Article: First Measurement of the $^33$Cl($p$,$alpha$)$^30$S Reaction

  C M Deibel, K E Rehm, J M Figueira, J P Greene, C -L Jiang, B P Kay, H Y Lee, J C Lighthall, S T Marley, R C Pardo, N Patel, M Paul, C Ugalde, A Woodard, A H Wuosmaa, G Zinkann
  Phys. Rev. C. 10/2011; 84(4):045802.
• Conference Proceeding: Studying the $alpha p$-process waiting points using Radioactive Ion Beams

  C M Deibel, M Alcorta, P F Bertone, J A Clark, C R Hoffman, C -L Jiang, B P Kay, H Y Lee, R C Pardo, K E Rehm, A M Rogers, J M Figueira, S Bedoor, D V Shetty, A H Wuosmaa, J C Lighthall, S T Marley, M Paul, C Ugalde
  Bulletin of the American Physical Society; 10/2011
• Conference Proceeding: Study of $^14$C$(alpha,gamma)^18$O using $n$- and $alpha$ transfer reactions with HELIOS

  H Y Lee, J P Schiffer, B B Back, J P Greene, C R Hoffman, B P Kay, K E Rehm, A H Wuosmaa, D V Shetty, J C Lighthall, S T Marley, C M Deibel
  Bulletin of the American Physical Society; 10/2011
• Conference Proceeding: Study of the $^9$C via the $d$($^10$C,$t$)$^9$C reaction

  S T Marley, A H Wuosmaa, S Bedoor, J C Lighthall, D V Shetty, M Alcorta, P F Bertone, J A Clark, C M Deibel, C -L Jiang, T Palchan-Hazan, R C Pardo, K E Rehm, A M Rogers, C Ugalde
  Bulletin of the American Physical Society; 10/2011
• Article: Study of valence neutrons in 136Xe with HELIOS

  B P Kay, J P Schiffer, S J Freeman, B B Back, S Bedoor, S I Baker, T Bloxham, J A Clark, C M Deibel, C R Hoffman, A M Howard, J C Lighthall, S T Marley, K E Rehm, D K Sharp, D V Shetty, J S Thomas, A H Wuosmaa
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  ABSTRACT: The single-neutron adding (d,p) reaction has been performed on 136Xe in inverse kinematics at 10 MeV/u. The position, time-of-flight, and energy of the outgoing protons were analyzed by the new helical orbit spectrometer, HELIOS, at Argonne National Laboratory. An excitation-energy resolution of 100 keV was obtained in the outgoing proton spectra. The experimental setup is described, along with a technique of extracting absolute cross sections. Data are shown which illustrate the performance of the device. This measurement clearly demonstrates the potential of HELIOS for future heavy radioactive-beam studies.
  Journal of Physics Conference Series 09/2011; 312(9):092034.
• Article: Single-neutron energies outside^{136} Xe

  B. P. Kay, J. P. Schiffer, S. J. Freeman, C. R. Hoffman, B. B. Back, S. I. Baker, S. Bedoor, T. Bloxham, J. A. Clark, C. M. Deibel, A. M. Howard, J. C. Lighthall, S. T. Marley, K. E. Rehm, D. K. Sharp, D. V. Shetty, J. S. Thomas, A. H. Wuosmaa
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  ABSTRACT: The single-neutron properties of the N=83 nucleus 137Xe have been studied using the 136Xe(d,p) reaction in inverse kinematics at a beam energy of 10 MeV/u. The helical-orbit spectrometer, HELIOS, at Argonne National Laboratory was used to analyze the outgoing protons, achieving an excitation-energy resolution of ∼100 keV. Extraction of absolute cross sections, angular distributions, and spectroscopic factors has led to a more complete understanding of the single-neutron strength in 137Xe. In particular, the centroids of the νh9/2 and νi13/2 strengths appear to evolve through the N=83 isotones in a manner consistent with the action of the tensor force.
  Phys. Rev. C. 08/2011; 84(2).
• Article: Investigations of three-, four-, and five-particle decay channels of levels in light nuclei created using a^{9} C beam

  R. J. Charity, J. M. Elson, J. Manfredi, R. Shane, L. G. Sobotka, B. A. Brown, Z. Chajecki, D. Coupland, H. Iwasaki, M. Kilburn, [......], W. G. Lynch, A. Sanetullaev, M. B. Tsang, J. Winkelbauer, M. Youngs, S. T. Marley, D. V. Shetty, A. H. Wuosmaa, T. K. Ghosh, M. E. Howard
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  ABSTRACT: The interactions of an E/A=70-MeV 9C beam with a Be target was used to populate levels in Be, B, and C isotopes, which undergo decay into many-particle exit channels. The decay products were detected in the HiRA array and the level energies were identified from their invariant mass. Correlations between the decay products were examined to deduce the nature of the decays, specifically to what extent all the fragments were created in one prompt step or whether the disintegration proceeded in a sequential fashion through long-lived intermediate states. In the latter case, information on the spin of the level was also obtained. Of particular interest is the five-body decay of the 8C ground state, which was found to disintegrate in two steps of two-proton decay passing through the 6Beg.s. intermediate state. The isobaric analog of 8Cg.s. in 8B was also found to undergo two-proton decay to the isobaric analog of 6Beg.s. in 6Li. A 9.69-MeV state in 10C was found to undergo prompt four-body decay to the 2p + 2α exit channel. The two protons were found to have a strong enhancement in the diproton region and the relative energies of all four p-α pairs were consistent with the 5Lig.s. resonance.
  Phys. Rev. C. 07/2011; 84(1).
• Conference Proceeding: Recent Results from HELIOS

  B B Back, S I Baker, S T Marley, P Mueller, R C Pardo, K E Rehm, A M Rogers, J P Schiffer, D V Shetty, A H Wuosmaa, J A Clark, C M Deibel, B J DiGiovine, S J Freeman, C R Hoffmann, B P Kay, H Y Lee, J C Lighthall
  Advances in Radioactive Isotope Science ARIS; 06/2011
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  Available from: ArXiv

  Article: Investigations of three, four, and five-particle exit channels of levels in light nuclei created using a 9C beam

  R. J. Charity, J. M. Elson, J. Manfredi, R. Shane, L. G. Sobotka, B A Brown, Z. Chajecki, D. Coupland, H Iwasaki, M. Kilburn, [......], W. G. Lynch, A. Sanetullaev, M. B. Tsang, J. Winkelbauer, M. Youngs, S. T. Marley, D V Shetty, A H Wuosmaa, T. K. Ghosh, M. E. Howard
  [show abstract] [hide abstract]
  ABSTRACT: The interactions of a E/A=70-MeV 9C beam with a Be target was used to populate levels in Be, B, and C isotopes which undergo decay into many-particle exit channels. The decay products were detected in the HiRA array and the level energies were identified from their invariant mass. Correlations between the decay products were examined to deduce the nature of the decays, specifically to what extent all the fragments were created in one prompt step or whether the disintegration proceeded in a sequential fashion through long-lived intermediate states. In the latter case, information on the spin of the level was also obtained. Of particular interest is the 5-body decay of the 8C ground state which was found to disintegrate in two steps of two-proton decay passing through the 6Beg.s. intermediate state. The isobaric analog of 8Cg.s. in 8B was also found to undergo two-proton decay to the isobaric analog of 6Beg.s. in 6Li. A 9.69-MeV state in 10C was found to undergo prompt 4-body decay to the 2p+2alpha exit channel. The two protons were found to have a strong enhancementin the diproton region and the relative energies of all four p-alpha pairs were consistent with the 5Lig.s. resonance.
  05/2011;
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  Available from: Richard C Pardo

  Article: Fusion reactions with the one-neutron halo nucleus (15)C.

  M Alcorta, K E Rehm, B B Back, S Bedoor, P F Bertone, C M Deibel, B DiGiovine, H Esbensen, J P Greene, C R Hoffmann, C L Jiang, J C Lighthall, S T Marley, R C Pardo, M Paul, A M Rogers, C Ugalde, A H Wuosmaa
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  ABSTRACT: The structure of (15)C, with an s(1/2) neutron weakly bound to a closed-neutron shell nucleus (14)C, makes it a prime candidate for a one-neutron halo nucleus. We have for the first time studied the cross section for the fusion-fission reaction (15)C+(232)Th at energies in the vicinity of the Coulomb barrier and compared it to the yield of the neighboring (14)C+(232)Th system measured in the same experiment. At sub-barrier energies, an enhancement of the fusion yield by factors of 2-5 was observed for (15)C, while the cross sections for (14)C match the trends measured for (12,13)C.
  Physical Review Letters 04/2011; 106(17):172701. · 7.37 Impact Factor
• Conference Proceeding: Single-neutron adding reactions outside the $N=50$ isotones

  D K Sharp, S J Freedman, B B Back, T Bloxham, J A Clark, C M Deibel, C R Hoffman, A M Howard, J C Lighthall, S T Marley, A J Mitchell, P D Parker, A M Rogers, J P Schiffer, J S Thomas, A H Wuosmaa
  Nuclear and Particle Physics Divisional Conference (NPPD); 04/2011
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  Available from: Burt Holzman

  Article: Charged-particle multiplicity and pseudorapidity distributions measured with the PHOBOS detector in Au+Au, Cu+Cu, d+Au, and p+p collisions at ultrarelativistic energies

  B. Alver, B. B. Back, M. D. Baker, M. Ballintijn, D. S. Barton, R. R. Betts, A. A. Bickley, R. Bindel, A. Budzanowski, W. Busza, [......], R. Verdier, G. I. Veres, B. Wadsworth, P. Walters, E. Wenger, F. L. H. Wolfs, B. Wosiek, K. Woźniak, A. H. Wuosmaa, B. Wysłouch
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  ABSTRACT: Pseudorapidity distributions of charged particles emitted in Au+Au, Cu+Cu, d+Au, and p+p collisions over a wide energy range have been measured using the PHOBOS detector at the BNL Relativistic Heavy-Ion Collider (RHIC). The centrality dependence of both the charged particle distributions and the multiplicity at midrapidity were measured. Pseudorapidity distributions of charged particles emitted with |η|<5.4, which account for between 95% and 99% of the total charged-particle emission associated with collision participants, are presented for different collision centralities. Both the midrapidity density dNch/dη and the total charged-particle multiplicity Nch are found to factorize into a product of independent functions of collision energy, √sNN, and centrality given in terms of the number of nucleons participating in the collision, Npart. The total charged particle multiplicity, observed in these experiments and those at lower energies, assumes a linear dependence of (lnsNN)2 over the full range of collision energy of √sNN=2.7–200 GeV.
  Phys. Rev. C. 02/2011; 83(2).