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18 results on '"Lambo, Ricardo"'

5. Towards Antihydrogen Trapping and Spectroscopy at ALPHA

Author

Butler, Eoin, Andresen, Gorm. B., Ashkezari, Mohammad. D., Baquero-Ruiz, Marcelo, Bertsche, William, Bowe, Paul D., Bray, Crystal C., Cesar, Claudio L., Chapman, Steven, Charlton, Michael, Fajans, Joel, Friesen, Tim, Fujiwara, Makoto C., Gill, David R., Hangst, Jeffrey S., Hardy, Walter N., Hayano, Ruyugo S., Hayden, Michael E., Humphries, Andrew J., Hydomako, Richard, Jonsell, Svante, Kurchaninov, Leonid, Lambo, Ricardo, Madsen, Niels, Menary, Scott, Nolan, Paul, Olchanski, Konstantin, Olin, Art, Povilus, Alexander, Pusa, Petteri, Robicheaux, Francis, Sarid, Eli, Silveira, Daniel M., So, Chukman, Storey, James W., Thompson, Robert I., van der Werf, Dirk P., Wilding, Dean, Wurtele, Jonathan S., and Yamazaki, Yasunori

Subjects
Physics - Atomic Physics, High Energy Physics - Experiment, Physics - Plasma Physics
Abstract

Spectroscopy of antihydrogen has the potential to yield high-precision tests of the CPT theorem and shed light on the matter-antimatter imbalance in the Universe. The ALPHA antihydrogen trap at CERN's Antiproton Decelerator aims to prepare a sample of antihydrogen atoms confined in an octupole-based Ioffe trap and to measure the frequency of several atomic transitions. We describe our techniques to directly measure the antiproton temperature and a new technique to cool them to below 10 K. We also show how our unique position-sensitive annihilation detector provides us with a highly sensitive method of identifying antiproton annihilations and effectively rejecting the cosmic-ray background., Comment: 10 pages, 5 figures

Published
2011
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6. Search For Trapped Antihydrogen

Author

Andresen, Gorm B., Ashkezari, Mohammad D., Baquero-Ruiz, Marcelo, Bertsche, William, Bowe, Paul D., Bray, Crystal C., Butler, Eoin, Cesar, Claudio L., Chapman, Steven, Charlton, Michael, Fajans, Joel, Friesen, Tim, Fujiwara, Makoto C., Gill, David R., Hangst, Jeffrey S., Hardy, Walter N., Hayano, Ryugo S., Hayden, Michael E., Humphries, Andrew J., Hydomako, Richard, Jonsell, Svante, Jørgensen, Lars V., Kurchaninov, Lenoid, Lambo, Ricardo, Madsen, Niels, Menary, Scott, Nolan, Paul, Olchanski, Konstantin, Olin, Art, Povilus, Alexander, Pusa, Petteri, Robicheaux, Francis, Sarid, Eli, Nasr, Sarah Seif El, Silveira, Daniel M., So, Chukman, Storey, James W., Thompson, Robert I., van der Werf, Dirk P., Wilding, Dean, Wurtele, Jonathan S., and Yamazaki, Yasunori

Subjects
Physics - Atomic Physics, High Energy Physics - Experiment
Abstract

We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9 positrons to produce 6 10^5 antihydrogen atoms, we have identified six antiproton annihilation events that are consistent with the release of trapped antihydrogen. The cosmic ray background, estimated to contribute 0.14 counts, is incompatible with this observation at a significance of 5.6 sigma. Extensive simulations predict that an alternative source of annihilations, the escape of mirror-trapped antiprotons, is highly unlikely, though this possibility has not yet been ruled out experimentally., Comment: 12 pages, 7 figures

Published
2010
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10. Calculation of the local environment of a barium monofluoride molecule in an argon matrix: A step towards using matrix-isolated BaF for determining the electron electric dipole moment

Author

Lambo, Ricardo L., Koyanagi, Gregory K., Ragyanszki, Anita, Horbatsch, Marko, Fournier, Rene, and Hessels, Eric A.

Subjects
Atomic Physics (physics.atom-ph), Biophysics, FOS: Physical sciences, Physics - Atomic and Molecular Clusters, Physical and Theoretical Chemistry, Atomic and Molecular Clusters (physics.atm-clus), Condensed Matter Physics, Molecular Biology, Physics - Atomic Physics
Abstract

The local environment of a barium monofluoride (BaF) molecule embedded in an argon matrix is calculated. A substitution of a BaF molecule for four Ar atoms is found to be strongly favoured compared to substitutions for other numbers of Ar atoms. The equilibrium positions of the BaF molecule and its nearby Ar neighbours are found by minimizing the total energy. The potential barrier that prevents the migration of the BaF molecule within the solid and the barrier that prevents its rotation are calculated. At the cryogenic temperatures used by the EDM$^3$ collaboration, these barriers are sufficiently large to fix the position and orientation of the molecule. Knowledge of the local environment of matrix-isolated BaF molecules is essential for the EDM$^3$ collaboration, which is using them in a precision measurement of the electron electric dipole moment., 6 pages, 3 figures. As published, with typos corrected in tables

Published
2022

12. Weakly Supervised Framework for Cancer Region Detection of Hepatocellular Carcinoma in Whole-Slide Pathologic Images Based on Multiscale Attention Convolutional Neural Network

Author

Diao, Songhui, Tian, yinli, Hu, Wanming, Hou, Jiaxin, Lambo, Ricardo, Zhang, Zhicheng, Xie, yaoqin, Nie, Xiu, Zhang, Fa, Racoceanu, Daniel, Qin, Wenjian, Daniel, Racoceanu, Shenzhen Institute of Advanced Technology [Shenzhen] (SIAT), Chinese Academy of Sciences [Beijing] (CAS), Sun Yat-sen University Cancer Center (SYSUCC), Stanford University, Huazhong University of Science and Technology [Wuhan] (HUST), CAS Institute of Computing Technology (ICT), Sorbonne Université (SU), Algorithms, models and methods for images and signals of the human brain (ARAMIS), Sorbonne Université (SU)-Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Institut du Cerveau = Paris Brain Institute (ICM), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Sorbonne Université (SU)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Institut National de la Santé et de la Recherche Médicale (INSERM)-CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut du Cerveau = Paris Brain Institute (ICM), Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Sorbonne Université (SU)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Institut du Cerveau et de la Moëlle Epinière = Brain and Spine Institute (ICM), Institut National de la Santé et de la Recherche Médicale (INSERM)-CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-CHU Pitié-Salpêtrière [AP-HP], Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Assistance publique - Hôpitaux de Paris (AP-HP) (AP-HP)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Institut du Cerveau et de la Moëlle Epinière = Brain and Spine Institute (ICM)

Subjects
Pathologists, Carcinoma, Hepatocellular, [INFO.INFO-TI]Computer Science [cs]/Image Processing [eess.IV], Liver Neoplasms, Humans, Attention, Neural Networks, Computer, ComputingMilieux_MISCELLANEOUS, Pathology and Forensic Medicine, [INFO.INFO-AI]Computer Science [cs]/Artificial Intelligence [cs.AI]
Abstract

Visual inspection of hepatocellular carcinoma cancer regions by experienced pathologists in whole-slide images (WSIs) is a challenging, labor-intensive, and time-consuming task because of the large scale and high resolution of WSIs. Therefore, a weakly supervised framework based on a multiscale attention convolutional neural network (MSAN-CNN) was introduced into this process. Herein, patch-based images with image-level normal/tumor annotation (rather than images with pixel-level annotation) were fed into a classification neural network. To further improve the performances of cancer region detection, multiscale attention was introduced into the classification neural network. A total of 100 cases were obtained from The Cancer Genome Atlas and divided into 70 training and 30 testing data sets that were fed into the MSAN-CNN framework. The experimental results showed that this framework significantly outperforms the single-scale detection method according to the area under the curve and accuracy, sensitivity, and specificity metrics. When compared with the diagnoses made by three pathologists, MSAN-CNN performed better than a junior- and an intermediate-level pathologist, and slightly worse than a senior pathologist. Furthermore, MSAN-CNN provided a very fast detection time compared with the pathologists. Therefore, a weakly supervised framework based on MSAN-CNN has great potential to assist pathologists in the fast and accurate detection of cancer regions of hepatocellular carcinoma on WSIs.

Published
2021

18. Infrared Spectroscopy of CO Isolated in Solid Nitrogen Matrix.

Author

Lei Wu, Lambo, Ricardo, Yan Tan, An-wen Liu, and Shui-ming Hu

Abstract

The infrared absorption spectra of the CO monomer isolated in solid N2 have been recorded at various temperatures between 4.5 and 30 K. The absorption features of the fundamental stretching mode show its linewidth and matrix-induced frequency shift to be weakly temperature-dependent. As the temperature of the matrix was raised, an increase in the linewidth together with a redshift in the central frequency was observed. These observations were explained in terms of the quenching of the CO rotational states by the N2 matrix into closely-lying librational states. A quantitative model was then used to calculate the energy difference between these librational states. Results show that they can be thermally populated through the absorption of matrix phonons. [ABSTRACT FROM AUTHOR]

Published
2014
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