21 results on '"C.P. Romero"'
Search Results
2. Measurement of beam asymmetry for π−Δ++ photoproduction on the proton at Eγ=8.5GeV
- Author
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E. S. Smith, T. Erbora, Ilya Larin, V. V. Tarasov, J. Schwiening, K. Luckas, B. E. Cannon, A. Austregesilo, C. Fanelli, A. Hurley, H. Marukyan, J. Fitches, R.S. Pedroni, W. McGinley, C. A. Meyer, L. Guo, J. Reinhold, A. Ali, T. D. Beattie, S. Furletov, M. M. Dalton, A. Smith, Z. Zhao, M. M. Ito, G. Rodriguez, F. Barbosa, D. Romanov, W. J. Briscoe, V. A. Matveev, A. M. Schertz, D. G. Ireland, V. Crede, T. Daniels, L. Gan, H. Egiyan, B. C.L. Sumner, A. LaDuke, G. J. Lolos, C. S. Akondi, V. Lyubovitskij, S. Somov, S. Fegan, R. Barsotti, S. Adhikari, M. R. Shepherd, A. Gasparian, E. Pooser, T. Whitlatch, N. Wickramaarachchi, Xiang Zhou, T. Britton, Sergey Kuleshov, B. Liu, M. Khatchatryan, H. Hakobyan, A. I. Ostrovidov, D. I. Lersch, K. Suresh, H. Li, P. Eugenio, W. B. Li, J. Barlow, Stephen Taylor, W. Phelps, J. Ritman, J. R. Stevens, M. McCaughan, Haiyan Gao, Mark Richard James Williams, Michael Dugger, Q. Zhou, Barry Ritchie, G. M. Huber, D. I. Sober, C. Gleason, K. Livingston, A. Thiel, A. Hamdi, I. I. Strakovsky, A. Schick, E. Barriga, V. S. Goryachev, A. Deur, Carlos A. Salgado, P. Pauli, V. Neelamana, Z. Baldwin, Z. Papandreou, O. Soto, R. Dzhygadlo, S. Schadmand, I. Jaegle, V. Khachatryan, J. Zarling, R. Dotel, Krisztian Peters, K. Goetzen, M. J. Amaryan, A. Asaturyan, F. Nerling, R. A. Schumacher, X. Shen, Christine Kourkoumelis, R. E. Mitchell, R. A. Miskimen, B. Zihlmann, L. Ng, A. Ernst, Zhiyong Zhang, V. V. Berdnikov, G. Vasileiadis, W.U. Boeglin, V. Kakoyan, D. J. Mack, D. Lawrence, Sean A Dobbs, A. Somov, William Brooks, Lubomir Pentchev, C. Paudel, A. M. Foda, G. Kalicy, N. S. Jarvis, A. Dolgolenko, S. Cole, O. Cortes, C.P. Romero, T. C. Black, R. T. Jones, M. E. McCracken, J. Zhou, K. Mizutani, M. Kamel, A. Teymurazyan, Y. Yang, and E. Chudakov
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Physics ,Range (particle radiation) ,GlueX ,Proton ,Meson ,010308 nuclear & particles physics ,media_common.quotation_subject ,Momentum transfer ,01 natural sciences ,Asymmetry ,Pseudoscalar ,Nuclear physics ,Pion ,0103 physical sciences ,High Energy Physics::Experiment ,Nuclear Experiment ,010306 general physics ,media_common - Abstract
We report a measurement of the π − photoproduction beam asymmetry for the reaction → γ p → π − Δ + + using data from the GlueX experiment in the photon beam energy range 8.2–8.8 GeV. The asymmetry Σ is measured as a function of four-momentum transfer t to the Δ + + and compared to phenomenological models. We find that Σ varies as a function of t : negative at smaller values and positive at higher values of | t | . The reaction can be described theoretically by t -channel particle exchange requiring pseudoscalar, vector, and tensor intermediaries. In particular, this reaction requires charge exchange, allowing us to probe pion exchange and the significance of higher-order corrections to one-pion exchange at low momentum transfer. Constraining production mechanisms of conventional mesons may aid in the search for and study of unconventional mesons. This is the first measurement of the process at this energy.
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- 2021
3. The GlueX beamline and detector
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T. Whitlatch, N. Wickramaarachchi, N. Cao, Ilya Larin, Michael Dugger, N. K. Walford, V. V. Tarasov, Gerard Visser, W. Phelps, J. Frye, B. Liu, J. Stewart, V. Razmyslovich, S. Schadmand, B. E. Cannon, C.P. Romero, O. Cortes, F. Nerling, S. Adhikari, M. M. Dalton, G. Voulgaris, C. S. Akondi, W. J. Briscoe, J. R. Stevens, W. D. Crahen, G.H. Biallas, H. Marukyan, R.S. Pedroni, C. Gleason, W. McGinley, P. Eugenio, E. Wolin, V. Crede, C. Carlin, L. A. Teigrob, F. Mokaya, T. C. Black, A. Toro, D. G. Meekins, I. A. Semenova, Elton Smith, A. Thiel, Kamal K. Seth, G. J. Lolos, A. M. Schertz, Todd Satogata, G. Kalicy, T. Daniels, N. S. Jarvis, A. Hamdi, I. I. Strakovsky, N. Qin, Mark Richard James Williams, I. Vega, A. Tsaris, Y. Yang, K. Goetzen, T. Erbora, J. Leckey, W. U. Boeglin, R. T. Jones, S. Fegan, D. S. Carman, K. Suresh, V. V. Berdnikov, Barry Ritchie, G. Vasileiadis, T. Carstens, E. Barriga, H. Al Ghoul, K. Moriya, J. Hardin, A. Gerasimov, M. E. McCracken, A. Deur, C. D. Keith, M. J. Staib, Hovanes Egiyan, A. Ali, Vladimir Popov, Jay Benesch, A. Hurley, C. Dickover, Viktor Matveev, Dmitri Romanov, A. Dolgolenko, B. Pratt, Justin I. McIntyre, C. A. Meyer, R. Mendez, A. R. Dzierba, C. Hutton, N. Sandoval, G. M. Huber, L. Guo, Z. Papandreou, Zhiyong Zhang, D. I. Sober, E. Pooser, J. Foote, J. Zarling, M. M. Ito, O. Chernyshov, Blake Leverington, S. Cole, P. Brindza, H. Hakobyan, A. Barnes, Sean A Dobbs, E. G. Anassontzis, T. D. Beattie, D. Werthmüller, X. Shen, Amiran Tomaradze, M. Patsyuk, J. Ritman, M. McCaughan, C. Fanelli, Yujie Qiang, R. A. Miskimen, A. Somov, R. Kliemt, F. Barbosa, A. Austregesilo, R. Dzhygadlo, C. Salgado, B. C.L. Sumner, L. Robison, Joerg Reinhold, Ting Xiao, A. Schick, V. Kakoyan, William Brooks, D. J. Mack, W. I. Levine, N. Gevorgyan, S. Katsaganis, E. Chudakov, Pavlos Ioannou, Lubomir Pentchev, A. Goncalves, A. Yu. Semenov, A. I. Ostrovidov, A. M. Foda, R. Dotel, M. Kamel, R. A. Schumacher, D. G. Ireland, W. B. Li, M. R. Shepherd, Ashot Gasparian, A. Teymurazyan, Krisztian Peters, J. Barlow, B. Zihlmann, Xiang Zhou, J. Pierce, S. Taylor, N. Sparks, L. Gan, S. Somov, L. Ng, A. Ernst, D. Kolybaba, K. Livingston, V. S. Goryachev, Cornelius Schwarz, P. Mattione, Y. Van Haarlem, P. Pauli, I. Tolstukhin, J. Schwiening, M. J. Amaryan, D. Lawrence, J. Brock, H. Ni, C. Stanislav, V. Lyubovitskij, S. Furletov, T. Britton, R. Barsotti, C. Paudel, Christine Kourkoumelis, Sergey Kuleshov, R. E. Mitchell, D. I. Lersch, C. L. Henschel, Q. Zhou, O. Soto, Friedrich Klein, and S.T. Krueger
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Nuclear and High Energy Physics ,GlueX, детектор ,Physics - Instrumentation and Detectors ,Photon ,Physics::Instrumentation and Detectors ,фотонный пучок ,FOS: Physical sciences ,Scintillator ,01 natural sciences ,Optics ,Hodoscope ,0103 physical sciences ,ddc:530 ,Nuclear Experiment (nucl-ex) ,010306 general physics ,Nuclear Experiment ,Instrumentation ,Physics ,GlueX ,Spectrometer ,Calorimeter (particle physics) ,010308 nuclear & particles physics ,business.industry ,Detector ,Instrumentation and Detectors (physics.ins-det) ,Beamline ,High Energy Physics::Experiment ,business - Abstract
The GlueX experiment at Jefferson Lab has been designed to study photoproduction reactions with a 9-GeV linearly polarized photon beam. The energy and arrival time of beam photons are tagged using a scintillator hodoscope and a scintillating fiber array. The photon flux is determined using a pair spectrometer, while the linear polarization of the photon beam is determined using a polarimeter based on triplet photoproduction. Charged-particle tracks from interactions in the central target are analyzed in a solenoidal field using a central straw-tube drift chamber and six packages of planar chambers with cathode strips and drift wires. Electromagnetic showers are reconstructed in a cylindrical scintillating fiber calorimeter inside the magnet and a lead-glass array downstream. Charged particle identification is achieved by measuring energy loss in the wire chambers and using the flight time of particles between the target and detectors outside the magnet. The signals from all detectors are recorded with flash ADCs and/or pipeline TDCs into memories allowing trigger decisions with a latency of 3.3 $\mu$s. The detector operates routinely at trigger rates of 40 kHz and data rates of 600 megabytes per second. We describe the photon beam, the GlueX detector components, electronics, data-acquisition and monitoring systems, and the performance of the experiment during the first three years of operation., Comment: Accepted by Nuclear Instruments and Methods A, 78 pages, 54 figures
- Published
- 2021
4. Measurement of the photon beam asymmetry in γ⃗p→K+Σ0 at Eγ=8.5 GeV
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T. D. Beattie, K. Goetzen, W. J. Briscoe, P. Pauli, G. M. Huber, D. I. Sober, M. J. Amaryan, V. Crede, M. M. Dalton, V. S. Goryachev, Christine Kourkoumelis, A. Hurley, R. E. Mitchell, G. Kalicy, N. S. Jarvis, C. A. Meyer, L. Ng, D. Lawrence, A. Ernst, H. Hakobyan, V. Lyubovitskij, G. J. Lolos, I. Larin, C. Salgado, R. Barsotti, S. Adhikari, O. Cortes, Sean A Dobbs, T. Britton, A. Somov, A. Ali, Sergey Kuleshov, C.P. Romero, P. Eugenio, R. A. Schumacher, D. I. Lersch, K. Livingston, M. M. Ito, Barry Ritchie, N. Cao, Ashot Gasparian, A. Hamdi, Krisztian Peters, Michael Dugger, T. C. Black, I. I. Strakovsky, J. Barlow, Joerg Reinhold, S. Fegan, A. Deur, S. Cole, J. Frye, E. Pooser, V. A. Matveev, N. Qin, J. Schwiening, O. Soto, A. M. Schertz, T. Whitlatch, L. Robison, T. Daniels, B. E. Cannon, T. Erbora, H. Ni, Z. Papandreou, Ting Xiao, V. V. Berdnikov, William Brooks, J. R. Stevens, M. McCaughan, Mark Richard James Williams, Lubomir Pentchev, C. Gleason, S. Furletov, Q. Zhou, A. M. Foda, Dmitri Romanov, H. Marukyan, R.S. Pedroni, W. U. Boeglin, W. McGinley, E. Chudakov, N. Wickramaarachchi, A. Thiel, K. K. Seth, C. Fanelli, M. Kamel, W. Phelps, F. Nerling, Elton Smith, B. Liu, G. Vasileiadis, A. Austregesilo, Zhiyong Zhang, M. R. Shepherd, A. Teymurazyan, R. T. Jones, Y. Yang, M. E. McCracken, Xiang Zhou, S. Taylor, L. Gan, S. Somov, L. Guo, J. Zarling, C. Paudel, A. Dolgolenko, V. V. Tarasov, E. Barriga, M. Patsyuk, J. Foote, X. Shen, K. Suresh, Hovanes Egiyan, R. A. Miskimen, R. Dzhygadlo, F. Barbosa, V. Kakoyan, D. J. Mack, A. Goncalves, R. Dotel, B. Zihlmann, A. I. Ostrovidov, H. Li, D. G. Ireland, and W. B. Li
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Physics ,Range (particle radiation) ,GlueX ,Spectrometer ,010308 nuclear & particles physics ,Linear polarization ,media_common.quotation_subject ,Theoretical models ,01 natural sciences ,Asymmetry ,Nuclear physics ,0103 physical sciences ,High Energy Physics::Experiment ,Photon beam ,Nuclear Experiment ,010306 general physics ,Beam (structure) ,media_common - Abstract
We report measurements of the photon beam asymmetry Σ for the reaction γp→K+Σ0 (1193) using the GlueX spectrometer in Hall D at Jefferson Lab. Data were collected by using a linearly polarized photon beam in the energy range of 8.2–8.8 GeV incident on a liquid hydrogen target. The beam asymmetry Σ was measured as a function of the Mandelstam variable t , and a single value of Σ was extracted for events produced in the u channel. These are the first exclusive measurements of the photon beam asymmetry Σ for the reaction in this energy range. For the t channel, the measured beam asymmetry is close to unity over the t range studied, − t = ( 0.1 – 1.4 ) ( GeV / c ) 2 , with an average value of Σ = 1.00 ± 0.05 . This agrees with theoretical models that describe the reaction via the natural-parity exchange of the K ∗ (892) Regge trajectory. A value of Σ = 0.41 ± 0.09 is obtained for the u channel integrated up to − u = 2.0 ( GeV / c ) 2 .
- Published
- 2020
5. Beam asymmetry Σ for the photoproduction of η and η′ mesons at Eγ=8.8GeV
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A. Hurley, L. Gan, C. A. Meyer, J. Frye, C. Paudel, V. V. Tarasov, A. Dolgolenko, H. Hakobyan, C. Salgado, A. M. Schertz, E. Barriga, T. Daniels, C. Fanelli, R. T. Jones, W. Phelps, F. Nerling, M. E. McCracken, Krisztian Peters, Michael Dugger, V. Kakoyan, M. J. Staib, B. E. Cannon, T. Erbora, E. Pooser, I. A. Semenova, Z. Zhang, V. A. Matveev, A. Barnes, Dmitri Romanov, Sean A Dobbs, V. V. Berdnikov, A. Hamdi, J. Barlow, I. I. Strakovsky, Mark Richard James Williams, K. Suresh, T. Whitlatch, A. Somov, T. C. Black, D. Lawrence, A. Thiel, M. M. Dalton, H. Marukyan, Hovanes Egiyan, L. Ng, A. Ernst, M. McCaughan, R.S. Pedroni, W. McGinley, G. M. Huber, D. I. Sober, L. Robison, K. Livingston, V. Lyubovitskij, A. Deur, Ting Xiao, Q. Zhou, R. A. Miskimen, William Brooks, X. Zhou, P. Eugenio, G. Zhao, N. Wickramaarachchi, O. Cortes, N. Qin, L. Guo, E. Chudakov, R. Barsotti, Lubomir Pentchev, N. Cao, O. Soto, K. K. Seth, R. Dzhygadlo, F. Barbosa, B. Zihlmann, S. Fegan, M. Kamel, A. M. Foda, D. J. Mack, R. A. Schumacher, N. Gevorgyan, T. Britton, A. I. Ostrovidov, B. Liu, V. Crede, C.P. Romero, G. J. Lolos, I. Larin, G. Vasileiadis, H. Li, Ashot Gasparian, Sergey Kuleshov, D. I. Lersch, D. G. Ireland, A. Goncalves, Z. Papandreou, V. S. Goryachev, M. J. Amaryan, P. Mattione, S. Adhikari, M. Patsyuk, W. B. Li, A. Yu. Semenov, R. Dotel, Elton Smith, J. Schwiening, Barry Ritchie, J. R. Stevens, S. Somov, M. Boer, J. Foote, J. Zarling, M. R. Shepherd, A. Teymurazyan, C. Gleason, G. Kalicy, N. S. Jarvis, X. Shen, A. Austregesilo, S. Cole, Christine Kourkoumelis, Joerg Reinhold, A. Ali, R. E. Mitchell, W. U. Boeglin, Y. Yang, M. M. Ito, P. Pauli, S. Furletov, W. J. Briscoe, T. D. Beattie, and K. Goetzen
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Physics ,GlueX ,Meson ,010308 nuclear & particles physics ,Linear polarization ,media_common.quotation_subject ,Momentum transfer ,Parity (physics) ,01 natural sciences ,7. Clean energy ,Asymmetry ,0103 physical sciences ,Quasiparticle ,Atomic physics ,Photon beam ,010306 general physics ,media_common - Abstract
We report on the measurement of the beam asymmetry Σ for the reactions → γ p → p η and → γ p → p η ′ from the GlueX experiment using an 8.2–8.8-GeV linearly polarized tagged photon beam incident on a liquid hydrogen target in Hall D at Jefferson Laboratory. These measurements are made as a function of momentum transfer − t with significantly higher statistical precision than our earlier η measurements and are the first measurements of η ′ in this energy range. We compare the results to theoretical predictions based on t -channel quasiparticle exchange. We also compare the ratio of Σ η to Σ η ′ to these models as this ratio is predicted to be sensitive to the amount of s ¯ s exchange in the production. We find that photoproduction of both η and η ′ is dominated by natural parity exchange with little dependence on − t .
- Published
- 2019
6. Tailoring magnetic properties of Co nanocluster assembled films using hydrogen
- Author
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Peter Lievens, H. Paddubrouskaya, C. Van Haesendonck, C.P. Romero, M. J. Van Bael, and Alexander Volodin
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Materials science ,Magnetic domain ,Hydrogen ,Analytical chemistry ,chemistry.chemical_element ,02 engineering and technology ,Coercivity ,equipment and supplies ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Condensed Matter::Materials Science ,Exchange bias ,Ferromagnetism ,chemistry ,0103 physical sciences ,Antiferromagnetism ,Thin film ,Magnetic force microscope ,010306 general physics ,0210 nano-technology ,human activities - Abstract
Tailoring magnetic properties in nanocluster assembled cobalt (Co) thin films was achieved by admitting a small percentage of H2 gas (∼2%) into the Co gas phase cluster formation chamber prior to deposition. The oxygen content in the films is considerably reduced by the presence of hydrogen during the cluster formation, leading to enhanced magnetic interactions between clusters. Two sets of Co samples were fabricated, one without hydrogen gas and one with hydrogen gas. Magnetic properties of the non-hydrogenated and the hydrogen-treated Co nanocluster assembled films are comparatively studied using magnetic force microscopy and vibrating sample magnetometry. When comparing the two sets of samples the considerably larger coercive field of the H2-treated Co nanocluster film and the extended micrometer-sized magnetic domain structure confirm the enhancement of magnetic interactions between clusters. The thickness of the antiferromagnetic CoO layer is controlled with this procedure and modifies the exchange bias effect in these films. The exchange bias shift is lower for the H2-treated Co nanocluster film, which indicates that a thinner antiferromagnetic CoO reduces the coupling with the ferromagnetic Co. The hydrogen-treatment method can be used to tailor the oxidation levels thus controlling the magnetic properties of ferromagnetic cluster-assembled films.
- Published
- 2018
7. Modified solar chimney configuration with a heat exchanger: Experiment and CFD simulation
- Author
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R. Gers, J.F. Levi, Rodolfo Feick, William Brooks, D.M. Aliaga, Mario Mery, and C.P. Romero
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Fluid Flow and Transfer Processes ,Cfd simulation ,Materials science ,Natural convection ,Solar chimney ,business.industry ,020209 energy ,02 engineering and technology ,Mechanics ,Computational fluid dynamics ,021001 nanoscience & nanotechnology ,Power (physics) ,Physics::Fluid Dynamics ,Heat exchanger ,0202 electrical engineering, electronic engineering, information engineering ,Chimney ,Power output ,0210 nano-technology ,business - Abstract
The performance of a modified solar chimney is studied numerically and experimentally. In this solar chimney, the classical solar collector array is replaced by a heat exchanger located in the middle section of the chimney. The natural convection inside is simulated by the commercial Computational Fluid Dynamics (CFD) code COMSOL. This software is used first to perform an optimization of the power output and to determine the optimal dimensions of the chimney prototype. From the parameters obtained numerically, a two-meter high chimney model is built to measure temperature profiles and power output of the chimney. The comparison between numerical and experimental results shows a difference lower than 6.2% for the power generated. Our prototype achieves a higher power density in comparison with other reported prototypes based on conventional solar chimney concept of similar height.
- Published
- 2021
8. Fabrication of Silver Nanoparticles Using a Gas Phase Nanocluster Device and Preliminary Biological Uses
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Mario Mery, Tomas P. Corrales, Cristian A. Acevedo, Simón Oyarzún, D.M. Aliaga, Werner Creixell, G. Herrera, F. Araneda, N. Orellana, and C.P. Romero
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0301 basic medicine ,Materials science ,Fabrication ,silver clusters ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,lcsh:Technology ,Article ,Silver nanoparticle ,03 medical and health sciences ,Sputtering ,gas phase clusters ,Cluster (physics) ,metallic clusters ,General Materials Science ,lcsh:Microscopy ,lcsh:QC120-168.85 ,lcsh:QH201-278.5 ,lcsh:T ,021001 nanoscience & nanotechnology ,myoblast cells ,Evaporation (deposition) ,Characterization (materials science) ,030104 developmental biology ,lcsh:TA1-2040 ,Transmission electron microscopy ,lcsh:Descriptive and experimental mechanics ,nanoparticles ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,lcsh:Engineering (General). Civil engineering (General) ,0210 nano-technology ,lcsh:TK1-9971 - Abstract
Nanoparticles can be used in a large variety of applications, including magnetic sensing, biological, superconductivity, tissue engineering, and other fields. In this study, we explore the fabrication of gas phase silver nanoparticles using a sputtering evaporation source. This setup composed of a dual magnetron cluster source holds several advantages over other techniques. The system has independent control over the cluster concentration and a wide range of cluster size and materials that can be used for the clusters and for the matrix where it can be embedded. Characterization of these silver nanoparticles was done using transmission electron microscopy (TEM). We obtain a lateral width of 10.6 nm with a dispersion of 0.24 nm. With atomic force microscopy (AFM) a Gaussian fit of this distribution yields and average height of 6.3 nm with a standard deviation of 1.4 nm. We confirm that the deposited silver nanoparticles have a homogenous area distribution, that they have a defined shape and size distribution, and that they are single standing nanoparticles. Given that the scientific literature is not precise regarding the toxic concentration of the nanoparticles, devices such as ours can help clarify these questions. In order to explore further biological applications, we have done preliminary experiments of cell spreading (myoblast adhesion), obtaining interesting morphological changes correlated with the silver concentration on the surface. With a deposited silver concentration ranging from 100&ndash, 620 ng/cm2, the cells showed morphological changes in a short time of 2 h. We conclude that this high precision nanoparticle fabrication technique is adequate for further biological research.
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- 2018
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9. Case study of a 4He evaporation refrigerator for polarized target experiments
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S. N. Santiesteban, C.P. Romero, D.M. Aliaga, Karl Slifer, Rodolfo Feick, D. Ruth, William Brooks, P. Bunout, and E. Long
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Physics ,Nuclear and High Energy Physics ,Work (thermodynamics) ,010308 nuclear & particles physics ,business.industry ,Multiphysics ,Design tool ,Refrigerator car ,Mechanical engineering ,Fluid mechanics ,Cryogenics ,Computational fluid dynamics ,01 natural sciences ,0103 physical sciences ,Heat transfer ,010306 general physics ,business ,Instrumentation - Abstract
In this work, we propose the use of Computational Fluid Dynamics (CFD) as a useful design tool for the construction and improvement of a vertical 4 He evaporation refrigerator. This approach provides a cost-effective solution for improving the performance of such systems designed through the use of traditional heat transfer and fluid mechanics-based relations. To this effect, we applied COMSOL Multiphysics to model an existing refrigerator, which had been built and extensively tested at the University of New Hampshire (UNH). This allowed us to firstly validate our methodology through contrast with reliable empirical data and subsequently to evaluate which modifications can contribute to improved performance. Our CFD based model accurately predicts the cooling power of the UNH design and provides insight into its operation. Moreover, the CFD case study we present here allowed us to propose and evaluate design modifications aimed at minimizing the heat load on the refrigerator.
- Published
- 2020
10. A new method for fabrication of cryo-solids for polarized targets
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D.M. Aliaga, V. Arredondo, Rodolfo Feick, William Brooks, H. Hakobyan, P. Bunout, Karl Slifer, R. Gers, and C.P. Romero
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Physics ,Nuclear and High Energy Physics ,Cylindrical geometry ,Fabrication ,business.industry ,Nuclear engineering ,Condenser (optics) ,Ready to use ,Computational fluid dynamics ,business ,Instrumentation ,Laboratory device ,Polarized target - Abstract
The design and test results for a prototype laboratory device capable of condensing and solidifying gases is presented. This equipment is a new approach to the fabrication of NH 3 material for polarized target experiments in nuclear physics experiments. The formed solids have a cylindrical geometry with 32 mm diameter and 50 mm height. With Computational Fluid Dynamics (CFD) analysis we designed and established operational parameters for the condenser. The system designed for initial testing with CO 2 is now ready to use for growing good quality crystals of NH 3 with a novel shape, featuring cooling channels for polarized target experiments.
- Published
- 2020
11. NPF: mirror development in Chile
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Michael J. Ireland, Pedro Mardones, Pedro Escárate, C.P. Romero, Hayk Hakobyan, Matthias R. Schreiber, Claudio Lobos, John Monnier, Jorge Cuadra, Stefan Kraus, L. Pedrero, N. Soto, Johan Olofsson, S. Zúñiga-Fernández, Elias Rozas, Amelia Bayo, and C. Rozas
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Computer science ,business.industry ,FOS: Physical sciences ,Substrate (printing) ,Wavefront sensor ,engineering.material ,Curvature ,Mandrel ,Wavelength ,Optics ,Coating ,Astronomical interferometer ,engineering ,Millimeter ,Astrophysics - Instrumentation and Methods for Astrophysics ,business ,Instrumentation and Methods for Astrophysics (astro-ph.IM) - Abstract
In the era of high-angular resolution astronomical instrumentation, where long and very long baseline interferometers (constituted by many, $\sim$ 20 or more, telescopes) are expected to work not only in the millimeter and submillimeter domain, but also at near and mid infrared wavelengths (experiments such as the Planet Formation Imager, PFI, see Monnier et al. 2018 for an update on its design); any promising strategy to alleviate the costs of the individual telescopes involved needs to be explored. In a recent collaboration between engineers, experimental physicists and astronomers in Valparaiso, Chile, we are gaining expertise in the production of light carbon fiber polymer reinforced mirrors. The working principle consists in replicating a glass, or other substrate, mandrel surface with the mirrored adequate curvature, surface characteristics and general shape. Once the carbon fiber base has hardened, previous studies have shown that it can be coated (aluminum) using standard coating processes/techniques designed for glass-based mirrors. The resulting surface quality is highly dependent on the temperature and humidity control among other variables. Current efforts are focused on improving the smoothness of the resulting surfaces to meet near/mid infrared specifications, overcoming, among others, possible deteriorations derived from the replication process. In a second step, at the validation and quality control stage, the mirrors are characterized using simple/traditional tools like spherometers (down to micron precision), but also an optical bench with a Shack-Hartman wavefront sensor. This research line is developed in parallel with a more classical glass-based approach, and in both cases we are prototyping at the small scale of few tens of cms. We here present our progress on these two approaches., Comment: 13 pages, SPIE Proceedings Volume 10700, Ground-based and Airborne Telescopes VII; 107003X (2018). Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States
- Published
- 2018
12. Construction and Performance of the Barrel Electromagnetic Calorimeter for the GlueX Experiment
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A. Toro, G. J. Lolos, Z. Papandreou, E. G. Anassontzis, Sergey Kuleshov, M.J. Staib, H. Hakobyan, C. A. Meyer, E. S. Smith, E. Chudakov, M. Shepherd, E.L. Plummer, William Brooks, Stephen Taylor, I. Vega, C. L. Henschel, Yujie Qiang, A. Yu. Semenov, A. M. Foda, O. Soto, M. M. Dalton, S.T. Krueger, C.P. Romero, W. McGinley, N. Sandoval, Christine Kourkoumelis, I. A. Semenova, Rimsky Alejandro Rojas, D. Lawrence, J. R. Stevens, T. Whitlatch, F. Barbosa, G. Vasileiadis, G. Voulgaris, C. Stanislav, S. Katsaganis, B. Zihlmann, W. Levine, and T. D. Beattie
- Subjects
Physics ,Nuclear and High Energy Physics ,Range (particle radiation) ,Physics - Instrumentation and Detectors ,GlueX ,Spectrometer ,010308 nuclear & particles physics ,Physics::Instrumentation and Detectors ,Detector ,Monte Carlo method ,FOS: Physical sciences ,Instrumentation and Detectors (physics.ins-det) ,01 natural sciences ,7. Clean energy ,Calorimeter ,Nuclear physics ,Silicon photomultiplier ,0103 physical sciences ,Calibration ,High Energy Physics::Experiment ,Nuclear Experiment (nucl-ex) ,010306 general physics ,Nuclear Experiment ,Instrumentation - Abstract
The barrel calorimeter is part of the new spectrometer installed in Hall D at Jefferson Lab for the GlueX experiment. The calorimeter was installed in 2013, commissioned in 2014 and has been operating routinely since early 2015. The detector configuration, associated Monte Carlo simulations, calibration and operational performance are described herein. The calorimeter records the time and energy deposited by charged and neutral particles created by a multi-GeV photon beam. It is constructed as a lead and scintillating-fiber calorimeter and read out with 3840 large-area silicon photomultiplier arrays. Particles impinge on the detector over a wide range of angles, from normal incidence at 90 degrees down to 11.5 degrees, which defines a geometry that is fairly unique among calorimeters. The response of the calorimeter has been measured during a running experiment and performs as expected for electromagnetic showers below 2.5 GeV. We characterize the performance of the BCAL using the energy resolution integrated over typical angular distributions for $\pi^0$ and $\eta$ production of $\sigma_E/E$=5.2\%/$\sqrt{E(\rm{GeV})} \oplus$ 3.6\% and a timing resolution of $\sigma$\,=\,150\,ps at 1\,GeV., Comment: 46 pages, 33 figures
- Published
- 2018
- Full Text
- View/download PDF
13. Coexistence of superconductivity and ferromagnetism in cluster-assembled Sn–Co nanocomposites
- Author
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André Vantomme, Kristiaan Temst, M. J. Van Bael, Kelly Houben, C.P. Romero, Enric Menéndez, Thomas Picot, and Maarten Trekels
- Subjects
Superconductivity ,Diffraction ,Phase boundary ,Nanocomposite ,Materials science ,Condensed matter physics ,Mechanical Engineering ,Metals and Alloys ,nanosystems ,Condensed Matter::Soft Condensed Matter ,cluster-assembled systems ,Condensed Matter::Materials Science ,Ferromagnetism ,Mechanics of Materials ,Conversion electron mössbauer spectroscopy ,Condensed Matter::Superconductivity ,nanocomposites ,morphology ,superconductor/ferromagnet hybrids ,Materials Chemistry ,Proximity effect (superconductivity) ,Cluster (physics) - Abstract
The coexistence of superconductivity and ferromagnetism is investigated in granular Sn-Co nanocomposites. The nanocomposites have been prepared by co-deposition of Sn atoms and Co clusters, the morphology and composition of which can be tuned by varying the deposition rate of Co clusters relative to Sn atoms. Flat isolated Sn islands are obtained at zero or low Co cluster flux, while granular nanocomposites are formed with increasing Co cluster flux, reaching Co concentrations up to 44 vol.%. Interfaces with a low electronic transparency between superconductor and ferromagnet are obtained by a combination of the granular nature of the nanocomposites and the formation of Sn-Co alloys at the Sn/Co interfaces. The structure and composition of the nanocomposites have been thoroughly characterized by atomic force microscopy, x-ray diffraction and conversion electron Mössbauer spectroscopy. Over the entire Co concentration range, the hybrids show a ferromagnetic response. The superconducting phase boundary and the Meissner response depend on the morphology and composition of the nanocomposites. In particular, the superconducting critical temperature decreases with increasing Co concentration, while the Meissner response varies from a reversible to a strongly hysteretic behaviour depending on the morphology of the samples with different Co content. The persistence of superconductivity at high Co concentrations is attributed to a suppression of the superconducting proximity effect in these nanocomposites, which is ascribed to the low interface transparency between the Sn and Co components that make up these hybrid systems. publisher: Elsevier articletitle: Coexistence of superconductivity and ferromagnetism in cluster-assembled Sn–Co nanocomposites journaltitle: Journal of Alloys and Compounds articlelink: http://dx.doi.org/10.1016/j.jallcom.2015.03.007 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved. ispartof: Journal of Alloys and Compounds vol:637 pages:509-516 status: published
- Published
- 2015
14. Quantitative determination of hydrogen absorption by Pd cluster-assembled films using a quartz crystal microbalance
- Author
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J.I. Avila, S. Rojas, R. El Far, Peter Lievens, C.P. Romero, D.E. Diaz-Droguett, and Alejandro L. Cabrera
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Materials science ,Hydrogen ,Metals and Alloys ,Analytical chemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,Quartz crystal microbalance ,Evaporation (deposition) ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Adsorption ,chemistry ,Materials Chemistry ,Atomic ratio ,Thin film ,Absorption (chemistry) ,Quartz - Abstract
We have measured hydrogen absorption capacity for a series of Pd films grown by two deposition techniques: a) flat films made with e-beam evaporation of Pd and b) films made of assembled Pd clusters. The films range in thickness from 9.5 to 45 nm. The technique implemented for measuring the amount of hydrogen absorbed by the films was a quartz crystal microbalance. The Pd films were grown on the quartz crystals and the change of mass due to the hydrogen absorption was determined from the shifting of the resonance frequency. Minute amounts of hydrogen absorbed of the order of nanograms per square centimeter can be detected by this technique. Plots of H/Pd atom ratio for each Pd film as a function of hydrogen pressure were obtained. The Pd e-beam grown films displayed a saturation H/Pd atomic ratio around 0.6 which is similar to bulk Pd. The Pd cluster film with a thickness of 14 nm displayed a remarkable absorption capacity with a ratio H Pd ≈ 0.84 .
- Published
- 2012
15. Unexpected large hydrogen adsorption by Nb cluster films under mild conditions of pressure and temperature
- Author
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C.P. Romero, J.I. Avila, Alejandro L. Cabrera, Peter Lievens, and R. Trabol
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Materials science ,Hydrogen ,Renewable Energy, Sustainability and the Environment ,Inorganic chemistry ,Analytical chemistry ,Niobium ,Oxide ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Manganese ,Condensed Matter Physics ,chemistry.chemical_compound ,Fuel Technology ,Adsorption ,chemistry ,Cluster (physics) ,sense organs ,Absorption (chemistry) ,Palladium - Abstract
Hydrogen absorption in several cluster assembled films was investigated by the optical and electrical response of the films when modified by hydrogen adsorption. The films were grown by deposition of niobium clusters and by co-deposition of niobium clusters with manganese or palladium clusters on sapphire and then capped by a thin Pd film. Unusual high adsorption of hydrogen by Nb clusters and thin metal oxide reductions at room temperature can be inferred by changes in optical transmission and resistance of the film. On the other hand, no hydrogen absorption can be inferred in the same experiments with co-deposited clusters of Nb and Pd and co-deposited clusters of Nb and Mn. The technique used in this work allows fast screening and detection of potential perm-selective materials for hydrogen.
- Published
- 2011
16. Pd as a promoter to reduce Co cluster films at room temperature
- Author
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R. Trabol, J.I. Avila, Huan Wang, Alejandro L. Cabrera, Peter Lievens, André Vantomme, M. J. Van Bael, and C.P. Romero
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Hydrogen ,Renewable Energy, Sustainability and the Environment ,Inorganic chemistry ,Analytical chemistry ,Oxide ,Energy Engineering and Power Technology ,chemistry.chemical_element ,Condensed Matter Physics ,Catalysis ,Hydrogen storage ,chemistry.chemical_compound ,Fuel Technology ,chemistry ,Desorption ,Thin film ,Cobalt ,Palladium - Abstract
The optical and resistivity properties of Pd/Co films are investigated and related to the interaction of palladium and the underlying cobalt (Co) clusters layer when exposed to hydrogen. Co is used because it is known to absorb hydrogen only on its surface. Co clusters with mean size of 1.8 nm in the gas phase were deposited on sapphire substrates at room temperature (RT), 300 °C, and 500 °C, respectively, and capped by a continuous Pd film. Light transmission and reflection in the visible range were measured during hydrogen exposure at different pressures in consecutive cycles. An unusual change in the transmittance and the resistance during the first hydrogenation cycle of a sample suggests that a reduction of the surface oxide on the Co clusters layer occurs at room temperature. The reduction of the native oxide on Co thin films or bulk does not happen without the Pd capping when exposed to hydrogen under similar conditions.
- Published
- 2010
17. Site-specific bio-functionalization of surfaces by means of metal nanostructures
- Author
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Margriet J. Van Bael, Carmen Bartic, Barbara Gysbrechts, C.P. Romero, Olivier Deschaume, Tobias Peissker, Kelly Houben, Danielle Rand, and Gloria Fabris
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chemistry.chemical_classification ,Materials science ,Nanostructure ,chemistry ,Biomolecule ,Molecular biophysics ,Surface modification ,Nanobiotechnology ,Nanotechnology ,Metal nanostructures ,Polymer ,Molecular beam epitaxy - Abstract
We present an approach to control the immobilization process of biomolecules by functionalization of SiO2substrates decorated with nanostructures. The creation of specific protein permissive and protein resistant areas leads to a directed and site-specific immobilization of proteins. We make use of molecular beam epitaxy and laser assisted cluster deposition to create Au nanostructures on PEG-silanized SiO2substrates. The chemical contrast provided by the two materials, namely Au and PEG on the substrate surface supports the specificity of thiol-based Au functionalization for biomolecule attachment. © 2012 IEEE. ispartof: pages:1-4 ispartof: 2012 12TH IEEE CONFERENCE ON NANOTECHNOLOGY (IEEE-NANO) pages:1-4 ispartof: IEEE International Conference on Nanotechnology (IEEE-NANO) location:Birmingham, UK date:20 Aug - 23 Aug 2012 status: published
- Published
- 2012
18. Atomic scale dynamics of ultrasmall germanium clusters
- Author
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Sara Bals, Emrah Yücelen, Koen Lauwaet, G. Van Tendeloo, Bart Partoens, S. Van Aert, B. Schoeters, C.P. Romero, Peter Lievens, and M. J. Van Bael
- Subjects
Microscopy, Electron, Scanning Transmission ,Materials science ,General Physics and Astronomy ,chemistry.chemical_element ,Nanotechnology ,Germanium ,02 engineering and technology ,Electron ,010402 general chemistry ,01 natural sciences ,Atomic units ,General Biochemistry, Genetics and Molecular Biology ,Article ,Ab initio quantum chemistry methods ,Microscopy ,Scanning transmission electron microscopy ,Cluster (physics) ,Multidisciplinary ,General Chemistry ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Characterization (materials science) ,chemistry ,Chemical physics ,0210 nano-technology ,Engineering sciences. Technology - Abstract
Starting from the gas phase, small clusters can be produced and deposited with huge flexibility with regard to composition, materials choice and cluster size. Despite many advances in experimental characterization, a detailed morphology of such clusters is still lacking. Here we present an atomic scale observation as well as the dynamical behaviour of ultrasmall germanium clusters. Using quantitative scanning transmission electron microscopy in combination with ab initio calculations, we are able to characterize the transition between different equilibrium geometries of a germanium cluster consisting of less than 25 atoms. Seven-membered rings, trigonal prisms and some smaller subunits are identified as possible building blocks that stabilize the structure., Ultrasmall clusters of atoms form the building blocks of many nanoscale materials. Using a combination of aberration-corrected transmission electron microscopy and numerical simulations, this study uncovers the geometry of these clusters in three dimensions.
- Published
- 2011
19. Superconductivity in Pb cluster assembled systems with different degrees of coagulation
- Author
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M. J. Van Bael, C.P. Romero, J. Cuppens, and Peter Lievens
- Subjects
Superconductivity ,High flux ,Materials science ,Condensed matter physics ,Condensed Matter::Superconductivity ,Cluster (physics) ,Magnetic response ,Thin film ,Condensed Matter Physics ,Critical field ,Electronic, Optical and Magnetic Materials ,Nanoclusters ,Laser vaporization - Abstract
Superconducting properties are observed and investigated in Pb nanogranular systems prepared by deposition of clusters produced in a laser vaporization cluster source. Different morphologies were achieved by controlling the degree of coagulation via the substrate temperature and the magnetic response of these systems was studied. Deposition on substrates at temperatures above $200\text{ }\ifmmode^\circ\else\textdegree\fi{}\text{C}$ results in an ensemble of weakly coupled islands showing superconducting confinement effects. Cluster deposition on cooled substrates limits the coagulation and results in cluster assembled thin films with strong intergrain coupling. This method provides a unique way to produce systems with very high flux pinning leading to avalanche effects.
- Published
- 2010
20. Hydrogen adsorption studies in micro-size cobalt dots
- Author
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Kristiaan Temst, E. Cisternas, Guerau Cabrera, J.I. Avila, C.P. Romero, Alejandro L. Cabrera, and Margriet J. Van Bael
- Subjects
Materials science ,Hydrogen ,Mechanical Engineering ,Analytical chemistry ,Thermal desorption ,chemistry.chemical_element ,Adsorption ,chemistry ,Transition metal ,Mechanics of Materials ,Chemisorption ,Desorption ,General Materials Science ,High-resolution transmission electron microscopy ,Cobalt - Abstract
Hydrogen desorption curves were obtained from a sample composed of a square arrangement of Co dots with average diameter of 4.4 μm, separated by a distance of 11.6 μm. A macroscopic sample of Co dots grown on a 2.5 × 2.5 cm Si substrate was made by standard lithographic techniques and used in these experiments. Thermal programmed desorption (TPD) was performed under ultra-high vacuum conditions. Hydrogen TPD curves were obtained from a 1 × 1 cm Co dots samples displaying a maximum of intensity at 425 K. Hydrogen TPD curve was also obtained from 1 cm× 1 cm samples of Co films and Co foils for comparison. The hydrogen TPD curves have decreasing intensity from the Co foils to the Co dots and finally to the Co films. This indicates that there are more sites for hydrogen adsorption on the Co dots than in the Co films. This is a surprising result because there is approximately 8.7 times less Co atoms exposed in the Co dots that in the Co film sample. A desorption energy of 27 kcal/mol was obtained for the Co dots suggesting that hydrogen is adsorbed on an hcp hollow site of the Co dot crystalline structure.
- Published
- 2007
21. Multicenter evaluation of assays for estradiol and progesterone in saliva
- Author
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S.B. Sufi, D Hazra, S C Gandy, S.L. Jeffcoate, H Goh, A. Donaldson, C.P. Romero, H Z Wang, and S Chearskul
- Subjects
Saliva ,Steroid hormone ,Serial sampling ,Multicenter study ,medicine.medical_treatment ,Biochemistry (medical) ,Clinical Biochemistry ,Immunology ,medicine ,Physiology ,Blood collection ,Biology ,Hormone - Abstract
Blood samples can be difficult to obtain in studies involving serial sampling, especially in developing countries where there may also be logistic, ethical, and cultural constraints that make frequent blood collection impractical. Assays for steroids in saliva may avoid some of these difficulties. A multicenter study involving laboratories in five countries was carried out to compare the results of assays for salivary estradiol and progesterone performed with centrally provided reagents and assay protocols. Concentrations of salivary steroid as obtained by all but one center were comparable with those reported in the literature. We conclude that assays of hormones in saliva are useful adjuncts to those performed on other body fluids.
- Published
- 1985
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