-
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
-
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 ^{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
-
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;
-
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).
-
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
[show abstract]
[hide abstract]
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
-
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
[show abstract]
[hide abstract]
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
-
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
-
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
-
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.
-
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
-
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
-
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
-
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
[show abstract]
[hide abstract]
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.
-
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
[show abstract]
[hide abstract]
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).
-
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 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).
-
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
-
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;
-
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
[show abstract]
[hide abstract]
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
-
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
-
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
[show abstract]
[hide abstract]
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).