Physical Sciences and Mathematics Commons^™

Utilizing Low-Cost Sensors To Monitor Indoor Air Quality In Mongolian Gers, Callum Flowerday, Jaron C. Hansen, Phil Lundrigan, Christopher Kitras

Faculty Publications

Air quality has important climate and health effects. There is a need, therefore, to monitor air quality both indoors and outdoors. Methods of measuring air quality should be cost-effective if they are to be used widely, and one such method is low-cost sensors (LCS). This study reports on the use of LCSs in Ulaanbataar, Mongolia to measure PM_2.5 concentrations inside yurts or “gers”. Some of these gers were part of a non-government agency (NGO) initiative to improve insulating properties of these housing structures. The goal of the NGO was to decrease particulate emissions inside the gers; a secondary result …

Does A Bottom-Up Mechanism Promote Hypoxia In The Mississippi Bight?, Virginie Sanial, Willard S. Moore, Alan M. Shiller

Faculty Publications

The Mississippi Bight, east of the Mississippi River, is a complex coastal ecosystem that, like the better-known Louisiana Shelf to the west, experiences seasonal bottom water hypoxia. However, input of allochthonous nutrients from the Mississippi River to the Mississippi Bight appears to be limited, begging the question of what drives seasonal hypoxia in this system. Prior research has suggested submarine groundwater discharge (SGD) could be an overlooked component of the Mississippi Bight biogeochemical system. We thus examined the hypothesis that SGD provides a “bottom up” driver for seasonal hypoxia in this area. We used a multi-tracer approach based on known …

Characterization Of The Differential Expressed Genes And Transcriptomic Pathway Analysis In The Liver Of Sub-Adult Red Drum (Sciaenops Ocellatus) Exposed To Deepwater Horizon Chemically Dispersed Oil, Tracy A. Sherwood, Maria L. Rodgers, Andrea M. Tarnecki, Dana L. Wetzel

Faculty Publications

The Deepwater Horizon blowout resulted in the second-largest quantity of chemical dispersants used as a countermeasure for an open water oil spill in the Gulf of Mexico. Of which, the efficacy of dispersant as a mitigation strategy and its toxic effects on aquatic fauna remains controversial. To enhance our understanding of potential sub-lethal effects of exposure to chemically dispersed-oil, sub-adult red drum (Sciaenops ocellatus) were continuously exposed to a Corexit 9500: DWH crude oil chemically enhanced water accommodated fraction (CEWAF) for 3-days and transcriptomic responses were assessed in the liver. Differential expressed gene (DEG) analysis demonstrated that 63 …

Privacy-Preserving Non-Participatory Surveillance System For Covid-19-Like Pandemics, Mahmoud Nabil, Ahmed Sherif, Mohamed Mahmoud, Waleed Alsmary, Maazen Alsabaan

Faculty Publications

COVID-19 pandemic has revealed a pressing need for an effective surveillance system to control the spread of infection. However, the existing systems are run by the people’s smartphones and without a strong participation from the people, the systems become ineffective. Moreover, these systems can be misused to spy on people and breach their privacy. Due to recent privacy breaches, people became anxious about their privacy, and without privacy reassurance, the people may not accept the systems. In this paper, we propose a non-participatory privacy-preserving surveillance system for COVID-19-like pandemics. The system aims to control the spread of COVID-19 infection without …

Measurements Of The Absolute Branching Fractions Of B± → K±Xcc, J. P. Lees, V. Poireau, V. Tisserand, E. Grauges

Faculty Publications

A study of the two-body decays B^±→X_ccK^±, where Placeholder refers to one charmonium state, is reported by the BABAR Collaboration using a data sample of 424 fb⁻¹. The absolute determination of branching fractions for these decays are significantly improved compared to previous BABARmeasurements. Evidence is found for the decay B⁺→ X ( 3872) K ⁺

at the Placeholder level. The absolute branching fraction Placeholder is measured for the first time. It follows that Placeholder, supporting the hypothesis of a molecular component for this resonance.

Perspectives On Chemical Oceanography In The 21st Century: Participants Of The Come Aboard Meeting Examine Aspects Of The Field In The Context Of 40 Years Of Disco, Andrea J. Fassbender, Hilary I. Palevsky, Todd R. Martz, Anitra E. Ingalls, Martha Gledhill, Sarah E. Fawcett, Jay A. Brandes, Lihini I. Aluwihare, The Participants Of Come Aboard, Disco Xxv, Christopher T. Hayes

Faculty Publications

The questions that chemical oceanographers prioritize over the coming decades, and the methods we use to address these questions, will define our field's contribution to 21st century science. In recognition of this, the U.S. National Science Foundation and National Oceanic and Atmospheric Administration galvanized a community effort (the Chemical Oceanography MEeting: A BOttom-up Approach to Research Directions, or COME ABOARD) to synthesize bottom-up perspectives on selected areas of research in Chemical Oceanography. Representing only a small subset of the community, COME ABOARD participants did not attempt to identify targeted research directions for the field. Instead, we focused on how best …

The Malina Oceanographic Expedition: How Do Changes In Ice Cover, Permafrost And Uv Radiation Impact On Biodiversity And Biogeochemical Fluxes In The Arctic Ocean?, Phillippe Massicotte, Rainer Amon, David Antoine, Philippe Archambault, Sergio Balzano, Simon Bélanger, Ronald Benner, Dominique Boeuf, Annick Bricaud, Flavienne Bruyant, Gwenaëlle Chaillou, Malik Malik, Bruno Charrière, Jing Chen, Hervé Claustre, Pierre Coupel, Nicole Delsaut, David Doxaran, Et. Al.

Faculty Publications

The MALINA oceanographic campaign was conducted during summer 2009 to investigate the carbon stocks and the processes controlling the carbon fluxes in the Mackenzie River estuary and the Beaufort Sea. During the campaign, an extensive suite of physical, chemical and biological variables was measured across seven shelf–basin transects (south-north) to capture the meridional gradient between the estuary and the open ocean. Key variables such as temperature, absolute salinity, radiance, irradiance, nutrient concentrations, chlorophyll-a concentration, bacteria, phytoplankton and zooplankton abundance and taxonomy, and carbon stocks and fluxes were routinely measured onboard the Canadian research icebreaker CCGS Amundsen and from a barge …

Peroxyl Radical Clocks, Bill Roschek, Keri A. Tallman, Christopher L. Rector, Jason G. Gillmore, Derek A. Pratt, Carlo Punta, Ned A. Porter

Faculty Publications

A series of peroxyl radical clocks has been developed and calibrated based on the competition between the unimolecular β-fragmentation (kβ) of a peroxyl radical and its bimolecular reaction with a hydrogen atom donor (kH). These clocks are based on either methyl linoleate or allylbenzene and were calibrated directly with α-tocopherol or methyl linoleate, which have well-established rate constants for reaction with peroxyl radicals (kH-tocopherol = 3.5 × 106 M-1 s-1, kH-linoleate = 62 M-1 s-1). This peroxyl radical clock methodology has been successfully applied to determine inhibition and propagation rate constants ranging from 100 to 107 M-1 s-1.

Isobaric Analog States As A Tool For Spectroscopy Of Exotic Nuclei, G. V. Rogachev, A. A. Aprahamian, F. D. Becchetti, P. Boutachkov, Y. Chen, G. Chubarian, P. A. Deyoung, A. Fomichev, V. Z. Goldberg, M. S. Golovkov, J. J. Kolata, Yu. Ts. Oganessian, Graham F. Peaslee, M. Quinn, A. Rodin, B. B. Skorodumov, R. S. Slepnev, G. Ter-Akopian, W. H. Trzaska, A. Wohr, R. Wolski

Faculty Publications

Spectroscopy of neutron rich exotic isotopes via their isobaric analog states (IAS) in less exotic nuclei is discussed. Several different experimental techniques, which can be applied to search for IAS of exotic isotopes, are described. Successful application of these techniques to the studies of heavy helium isotopes7He and 9He led to the observation of unknown IAS in 7Li and 9Li. Spectroscopic information for these states were obtained, and implication of these findings to the structure of 7,9He is considered.

Quantum Amplified Isomerization:  A New Concept For Polymeric Optical Materials, Jason G. Gillmore, J. D. Neiser, K. A. Mcmanus, Y. Roh, G. W. Dombrowski, T. G. Brown, J. P. Dinnocenzo, S. Farid, D. R. Robello

Faculty Publications

The preparation and evaluation of a new class of photoresponsive polymers are described on the basis of a process called quantum amplified isomerization (QAI). The QAI process utilizes photoinitiated, cation radical isomerization chemistry in a polymeric medium. Two classes of materials are described:  one where the QAI reactant is molecularly doped in the polymer matrix and another where the reactant is part of a functionalized polymer. Quantum yield experiments demonstrate that the isomerization reaction can proceed by a chain process with modest efficiencies. Photochemical conversion experiments show that high extents of conversion of the QAI reactants are possible. The rate …

A-Stripping Reactions With Exotic Nuclei: 12c7be,3he)16o, H. Amro, F. D. Becchetti, Yu Chen, H. Jiang, M. Ojaruega, H. C. Griffin, J. J. Kolata, B. B. Skorodumov, J. D. Hinnefeld, Graham F. Peaslee

Faculty Publications

The 12C(7Be,3He)16O reaction has been studied at E(7Be)=34 MeV. At this energy this Reaction exhibits a high selectivity for populating known α‐cluster states in 16O (Jπ = 0+,3−,2+,1−,4+, and 6+). The angular distributions for the 0+,3−,2+,1−, and 4+ levels are obtained at forward angles. Likewise, large reaction rates were measured for the 3He transfer channel, i.e. 12C(7Be,α)15O

Doppler Shift As A Tool For Studies Of Resonant (P,N) Reactions With Ribs: Spectroscopy Of 7he, P. Boutachkov, G. V. Rogachev, V. Z. Goldberg, A. Aprahamian, F. D. Becchetti, J. P. Bychowski, Y. Chen, G. Chubarian, P. A. Deyoung, J. J. Kolata, L. O. Lamm, Graham F. Peaslee, M. Quinn, B. B. Skorodumov, A. Wöhr

Faculty Publications

We report on a new methods for studies of neutron rich systems through resonant (p,n) reaction with radioactive ion beams. A specific example of the spectroscopy of 7He and future application of the proposed methods are discussed.

Cyclopropylcarbinyl → Homoallyl-Type Ring Opening Of Ketyl Radical Anions. Structure/Reactivity Relationships And The Contribution Of Solvent/Counterion Reorganization To The Intrinsic Barrier, J. M. Tanko, Jason G. Gillmore, Robert Friedline, M'Hamed Chahma

Faculty Publications

Following a protocol developed by Mathivanan, Johnston, and Wayner (J. Phys. Chem. 1995, 99, 8190−8195), the radical anions of several cyclopropyl- and oxiranyl-containing carbonyl compounds were generated in an effort to measure the rate constants for their ring opening (ko) by laser flash photolysis. The results of these experiments are compared to those obtained from earlier electrochemical studies, and the combined data set is used to rationalize the kinetics of radical anion ring opening in a general context by using Savéant's theory pertaining to stepwise dissociative electron transfer (Acc. Chem. Res. 1993, 26, 455−461). Compared to cyclopropylcarbinyl → homoallyl rearrangements …

Two-Neutron Transfer In The 6he + 209bi Reaction Near The Coulomb Barrier, Paul A. Deyoung, Patrick J. Mears, J. J. Kolata, E. F. Aguilera, F. D. Becchetti, Y. Chen, M. Cloughesy, H. Griffin, C. Guess, J. D. Hinnefeld, H. Jiang, Scott R. Jones, U. Khadka, D. Lizcano, E. Martinez-Quiroz, M. Ojaniega, Graham F. Peaslee, A. Pena, J. Reith, S. Vandendriessche, J. A. Zimmerman

Faculty Publications

The cross section for α-particle emission in the He6+Bi209 reaction at energies near the Coulomb barrier is remarkably large. Possible reactions that may produce the observed α particles include two-neutron transfer, one-neutron transfer, and direct projectile breakup. Each of these mechanisms results in a distinctive angular correlation between the α particle and the outgoing neutron(s). A neutron-α-particle coincidence experiment was performed to study two-neutron transfer to unbound states of Bi211. It is shown that approximately 55% of the observed α-particle yield at and beyond the grazing angle is because of this process. This is more than 2.5 times the fraction …

Isobaric Analog States Of Neutron-Rich Nuclei. Doppler Shift As A Measurement Tool For Resonance Excitation Functions, P. Boutachkov, G. V. Rogachev, V. Z. Goldberg, A. Aprahamian, F. D. Becchetti, J. P. Bychowski, Y. Chen, G. Chubarian, P. A. Deyoung, J. J. Kolata, L. O. Lamm, Graham F. Peaslee, M. Quinn, B. B. Skorodumov, A. Wohr

Faculty Publications

We present a new approach for the measurement of resonance excitation functions of neutron-rich nuclei using Doppler shift information. Preliminary data from the first application of the method is presented in the spectroscopy studies of 7He isobaric analog states in 7Li.

Quantum Amplified Isomerization: A New Chemically Amplified Imaging System In Solid Polymers, Douglas R. Robello, Joseph P. Dinnocenzo, Samir Farid, Jason G. Gillmore, Samuel W. Thomas Iii

Faculty Publications

A new imaging system based on a photoinitiated electron transfer chain reaction is reported. Specifically, irradiation of 9,10-dicyanoanthracene (sensitizer) leads to the conversion of Dewar benzene derivatives (reactants) to benzene derivatives (products) within solid polymer films. The mechanism of the reaction may involve chemical amplification with cation radicals ("holes") as the catalytic species. We present herein studies of both molecularly doped polymers and polymers containing Dewar benzene moieties attached to side chains. The refractive index of the materials could be tuned within a narrow range using this photochemical reaction, as demonstrated by the writing of persistent gratings in forced Rayleigh …

A High Throughput Method For The Conversion Of Co2 Obtained From Biochemical Samples To Graphite In Septa-Sealed Vials For Quantification Of 14c Samples Via Accelerator Mass Spectrometry, Ted J. Ognibene, Graham Bench, John S. Vogel, Graham F. Peaslee, Steve Murov

Faculty Publications

The growth of accelerator mass spectrometry as a tool for quantitative isotope ratio analysis in the biosciences necessitates high-throughput sample preparation. A method has been developed to convert CO2 obtained from carbonaceous samples to solid graphite for highly sensitive and precise 14C quantification. Septa-sealed vials are used along with commercially available disposable materials, eliminating sample cross contamination, minimizing complex handling, and keeping per sample costs low. Samples containing between 0.25 and 10 mg of total carbon can be reduced to graphite in 4 h in routine operation. Approximately 150 samples per 8-h day can be prepared by a single technician.

A New Accelerator Mass Spectrometry System For 14c-Quantification Of Biochemical Samples, Ted J. Ognibene, Graham Bench, Tom A. Brown, Graham F. Peaslee, John S. Vogel

Faculty Publications

A compact accelerator mass spectrometry (AMS) system that meets our requirements for View the MathML source-quantification of biochemical samples is described. The spectrometer occupies approximately 5 m2 of floor space and can measure >300 samples per day with 3% precision. A long diffuse gas cell is used to destroy interfering molecules and to charge exchange injected negative ions. System sensitivity is <1 amol View the MathML source/mg carbon on milligram-sized samples with a dynamic range that extends over 4 orders magnitude. All components, with the exception of the ion source, are commercially available and the system operates reliably with low maintenance.

A Statistical Interpretation Of The Correlation Between Imf Multiplicity And Transverse Energy, L. Phair, L. Beaulieu, L. G. Moretto, G. J. Wozniak, D. R. Bowman, N. Carlin, L. Celano, N. Colonna, J. D. Dinius, A. Ferrero, C. K. Gelbke, T. Glasmacher, F. Gramegna, D. O. Handzy, W. C. Hsi, M. J. Huang, I. Iori, Y. D. Kim, M. A. Lisa, W. G. Lynch, G. V. Margagliotti, P. F. Mastinu, P. M. Milazzo, C. P. Montoya, A. Moroni, Graham F. Peaslee, R. Rui, C. Schwarz, M. B. Tsang, K. Tso, G. Vannini, F. Zhu

Faculty Publications

Multifragment emission following 129Xe+197Au collisions at 30A, 40A, 50A, and 60A MeV has been studied with multidetector systems covering nearly 4π in solid angle. The correlations of both the intermediate mass fragment and light charged particle multiplicities with the transverse energy are explored. A comparison is made with results from a similar system 136Xe+209Bi at 28A MeV. The experimental trends are compared to statistical model predictions.

The Benign Hamburger, Graham F. Peaslee, Juliette Lantz, Mary Walczak

Faculty Publications

In this dilemma case study, the executives of a popular restaurant chain must decide whether to use irradiated meat, in this case, beef, to protect its customers from the bacteria, E. coli. Students learn about food irradiation and discuss issues related to food safety and the public’s acceptance of new food technologies. As developed, the case could be used in a variety of introductory science courses in chemistry, physics, biology, environmental science, and agricultural science.

A Comparison Between Pixe Studies And Electron Microprobe Studies Of Rocks From Southern India., Graham F. Peaslee, D. A. Carlson, E. C. Hansen, S. S. Hendrickson, R. J. Timmer, A. L. Van Wyngarden, J. D. Wilcox

Faculty Publications

The Hope College PIXE facility was used to perform an analysis of zircons, apatites and monazites prevalent in rocks collected in southern India. Thin sections of the samples were prepared for electron microprobe analysis at U. Chicago, and a number of rare earth elements were quantitatively measured. These samples were then fractured and individual crystals were analyzed with 2.3 MeV protons in an internal PIXE irradiation chamber. GUPIX II© software was used to identify and measure trace metals in the samples and the results have been correlated with the electron microprobe data. Whole rock analyses, prepared by making pressed pellets …

Impact Parameter Dependence Of Light Charged Particle Production In 25 A Mev 16o On Tb, Ta And 35 A Mev 14n On Sm And Ta, D. Prindle, A. Elmaani, C. Hyde-Wright, W. Jiang, A. A. Sonzogni, R. Vandenbosch, D. Bowman, G. Cron, P. Danielewicz, J. Dinius, W. Hsi, W. G. Lynch, C. Montoya, Graham F. Peaslee, C. Schwarz, M. B. Tsang, C. Williams, R. T. De Souza, D. Fox, T. Moore

Faculty Publications

The impact parameter dependence of light charged particle (p,d,t,α) emission has been studied using an impact parameter selection based on coincident detection of residues or fission fragments. The energy spectra at twelve angles between 20° and 150° have been fit by a multiple moving source parametrization. The angle and energy integrated preequilibrium proton multiplicities decrease with increasing impact parameter in qualitative agreement with a Fermi jet calculation. The preequilibrium d/p and t/p multiplicities increase slowly with increasing impact parameter and are nearly identical at the two bombarding energies. The preequilibrium α/p ratio shows a less consistent dependency on impact parameter …

Disappearance Of Rotational Flow And Reaction Plane Dispersions In Kr+Au Collisions, W. Q. Shen, M. B. Tsang, N. Carlin, R. J. Charity, J. Feng, C. K. Gelbke, W. C. Hsi, M. J. Huang, G. J. Kunde, M-C. Lemaire, M. A. Lisa, W. G. Lynch, U. Lynen, Y. G. Ma, Graham F. Peaslee, L. Phair, J. Pochodzalla, H. Sann, C. Schwarz, L. G. Sobotka, R. T. De Souza, S. R. Souza, W. Trautmann, C. Williams

Faculty Publications

Two-particle azimuthal correlations have been used to extract reaction plane dispersion free triple-differential cross sections for d, t, and α particles for the midcentral collisions of 84Kr+197Au at E/A=35, 55, and 70 MeV. Both experimental measurements and extrapolations from lower incident energies suggest that rotational flow disappears at E/A≈100 MeV for light charged particles and that reaction plane dispersions introduce large uncertainties in extracting the disappearance of rotational flow.

Radical Ion Probes. 8. Direct And Indirect Electrochemistry Of 5,7-Di-Tert-Butylspiro[2.5]Octa-4,7-Dien-6-One And Derivatives, J. Paige Phillips, Jason G. Gillmore, Phillip Schwartz, Larry E. Brammer Jr., Daniel J. Berger, J. M. Tanko

Faculty Publications

Results pertaining to the direct and indirect electrochemistry of 5,7-di-tert-butylspiro[2.5]octa-4,7-dien-6-one (1a), 1-methyl-5,7-di-tert-butylspiro[2.5]octa-4,7-dien-6-one (1b), and 1,1,-dimethyl-5,7-di-tert-butylspiro[2.5]octa-4,7-dien-6-one (1c) are reported. Product analyses reveal that reduction of all these substrates leads to cyclopropane ring-opened products; ring opening occurs with modest selectivity leading to the more substituted (stable) distonic radical anion. The direct electrochemistry of these compounds is characterized by rate limiting electron transfer (with α ≈ 0.5), suggesting that while ring opening is extremely rapid, the radical anions do have a discrete lifetime (i.e., electron transfer and ring opening are not concerted). Utilizing homogeneous redox catalysis, rate constants for electron transfer between 1a, …

Fragment Distributions For Highly Charged Systems, C. Williams, W. G. Lynch, C. Schwarz, M. B. Tsang, W. C. Hsi, M. J. Huang, D. R. Bowman, J. Dinius, C. K. Gelbke, D. O. Handzy, G. J. Kunde, M. A. Lisa, Graham F. Peaslee, L. Phair, A. Botvina, M-C. Lemaire, S. R. Souza, G. Van Buren, R. J. Charity, L. G. Sobotka, U. Lynen, J. Pochodzalla, H. Sann, W. Trautmann, D. Fox, R. T. De Souza, N. Carlin

Faculty Publications

Charge and transverse energy distributions for intermediate mass fragments have been extracted for central 84Kr+197Au collisions at E/A=35-400 MeV. The slopes of the measured fragment charge distributions decrease monotonically with incident energy, consistent with the expectations for highly charged systems, but not with recent critical exponent analyses. Statistical model calculations, which reproduce the experimental trends, suggest that post-breakup fragment secondary decays alter significantly the observed charge distributions. Radial expansion velocities extracted from these calculations follow the systematics of Au+Au collisions.

Fragment Multiplicity Dependent Charge Distributions In Heavy Ion Collisions, M. B. Tsang, C. Williams, M. J. Huang, W. G. Lynch, L. Phair, D. R. Bowman, J. Dinius, C. K. Gelbke, D. O. Handzy, W. C. Hsi, G. J. Kunde, M. A. Lisa, Graham F. Peaslee, A. Botvina, M-C. Lemaire, S. R. Souza, G. Van Buren, R. J. Charity, L. G. Sobotka, C. Schwarz, U. Lynen, J. Pochodzalla, H. Sann, W. Trautmann, D. Fox, R. T. De Souza, N. Carlin

Faculty Publications

The dependence of intermediate-mass-fragment (IMF) element distributions on the multiplicity, NIMF, of detected fragments has been measured for 84Kr+197Au collisions at E/A=35, 55, 70, 100, 200, and 400 MeV. The observed dependence can be parametrized as P(NIMF|Z)∝P(Z)exp(-c⋅NIMF⋅Z), where c is a beam-energy and excitation-energy dependent parameter. Previous work indicated this parameter is zero in the liquid-gas coexistence region and positive in the gaseous phase. In contrast, we observe both negative and positive values for c, revealing the meaning of this parameter to be less straightforward than previously assumed. The magnitude of c appears nonetheless to provide a nontrivial test of …

Investigating The Evolution Of Multifragmenting Systems With Fragment Emission Order, E. W. Cornell, T. M. Hamilton, D. Fox, Y. Lou, R. T. De Souza, M. J. Huang, W. C. Hsi, C. Schwarz, C. Williams, D. R. Bowman, J. Dinius, C. K. Gelbke, D. O. Handzy, M. A. Lisa, W. G. Lynch, Graham F. Peaslee, L. Phair, M. B. Tsang, G. Vanburen, R. J. Charity, L. G. Sobotka, W. A. Friedman

Faculty Publications

Multifragment decays of central collisions in 84Kr+197Au at E/A=70MeV are studied. By utilizing a technique sensitive to the emission order of fragments, it is deduced that carbon fragments are emitted prior to beryllium fragments when these fragments have the same velocity. This observation is consistent with the cooling of a thermally decaying source.

Searching For The Nuclear Liquid-Gas Phase Transition In Au + Au Collisions At 35 Mev/Nucleon, M. Belkacem, P. F. Mastinu, V. Latora, A. Bonasera, M. D'Agostino, M. Bruno, J. D. Dinius, M. L. Fiandri, F. Gramegna, D. O. Handzy, W. C. Hsi, M. Huang, G. V. Margagliotti, P. M. Milazzo, C. P. Montoya, Graham F. Peaslee, R. Rui, C. Schwarz, G. Vannini, C. Williams

Faculty Publications

Within the framework of classical molecular dynamics, we study the collision Au+Au at an incident energy of 35 MeV/nucleon. It is found that the system shows a critical behavior at peripheral impact parameters, revealed through the analysis of conditional moments of charge distributions, Campi scatter plot, and the occurrence of large fluctuations in the region of the Campi plot where this critical behavior is expected. When applying the experimental filters of the MULTICS-MINIBALL apparatus, it is found that criticality signals can be hidden due to the inefficiency of the experimental apparatus. The signals are recovered by identifying semiperipheral and peripheral …

Mass Dependence Of Directed Collective Flow, M. J. Huang, R. C. Lemmon, F. Daffin, W. G. Lynch, C. Schwarz, M. B. Tsang, C. Williams, P. Danielewicz, K. Haglin, W. Bauer, N. Carlin, R. J. Charity, R. T. De Souza, C. K. Gelbke, W. C. Hsi, G. J. Kunde, M. C. Lemaire, M. A. Lisa, U. Lynen, Graham F. Peaslee, J. Pochodzalla, H. Sann, L. G. Sobotka, S. R. Souza, W. Trautmann

Faculty Publications

Sidewards directed fragment flow has been extracted for 84Kr+197Au collisions at E/A=200MeV, using techniques that are free of reaction plane dispersion. The fragment flow per nucleon increases with mass, following a thermal or coalescencelike behavior, and attains roughly constant limiting values at 4≤A≤12. Comparisons of the impact parameter dependences of the measured coalescence-invariant proton flow to Boltzmann-Uehling-Uhlenbeck calculations clearly favor a momentum dependent nuclear mean field.

Universality Of Spectator Fragmentation At Relativistic Bombarding Energies, A. Schüttauf, W. D. Kunze, A. Wörner, M. Begemann-Blaich, Th. Blaich, D. R. Bowman, R. J. Charity, A. Cosmo, A. Ferrero, C. K. Gelbke, C. Groß, W. C. Hsi, J. Hubele, G. Immé, I. Iori, J. Kempter, P. Kreutz, G. J. Kunde, V. Lindenstruth, M. A. Lisa, W. G. Lynch, U. Lynen, M. Mang, T. Möhlenkamp, A. Moroni, W. F.J. Müller, M. Neumann, B. Ocker, C. A. Ogilvie, Graham F. Peaslee, J. Pochodzalla, G. Raciti, F. Rosenberger, Th. Rubehn, H. Sann, C. Schwarz, W. Seidei, V. Serfling

Faculty Publications

Multi-fragment decays of 129Xe, 197Au and 238U projectiles in collisions with Be, C, Al, Cu, In, Au and U targets at energies between View the MathML source and 1000 MeV have been studied with the ALADIN forward-spectrometer at SIS. By adding an array of 84 SiCsI(Tl) telescopes the solid-angle coverage of the setup was extended to θlab = 16°. This permitted the complete detection of fragments from the projectile-spectator source. The dominant feature of the systematic set of data is the Zbound universality that is obeyed by the fragment multiplicities and correlations. These observables are invariant with respect to the …