Browsing by Author "Li, J."

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    Analysis of delivery and recalculation of dose using DICOM treatment records
    (Elsevier, 2022) Chen, Z.; Moyers, M.F.; Deng, Y.; Chen, H.L.; Li, J.; Shen, Z.M.; Lin, J.; Wang, Q.; Yepes, P.
    Objective A procedure has been proposed for patient-specific QA that, instead of comparing a measurement to the planned dose, compares the dose calculated by an independent system to the dose calculated by the planning system. It is still prudent, however, to check the accuracy of the beam delivery. For this purpose, the DICOM records from the first treatment fraction can be compared to the planned treatment using an in-house developed planning system. Methods Totally 1,398 patient portals were subjected to the new QA procedure. The dose distribution for each portal was first recalculated on a water phantom by two treatment planning systems and the dose distributions were compared. When agreement was observed, the patient was allowed to start treatment without a measurement. The record from the first day was imported into an in-house planning system which was used to evaluate the delivery for errors and calculate the delivered dose distribution and compare it to the planned dose distribution. Results A total of 266 portals passed a strict comparison between the clinical and QA dose calculations and directly used for treatment without measurements. For those portals, the comparison of the delivery records to the plan showed that 99% of spot positions deviated less than 0.2 ​mm and 99.7% of spot metersets deviated by less than 0.3%. On the other hand, 64 portals showed spot size deviations greater than the tolerance of ± 15% with some as large as ±25%. For 32 portals in which the record was used to calculate the delivered dose distribution, the Gamma passing rates between the planned and delivered distributions were always above 95% using a 2% dose difference and 2 ​mm distance-to-agreement criteria. Conclusions The new QA process has been implemented slowly with strict constraints. The amount of beam time required has been reduced while maintaining safety.
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    Fermi-LAT Observations of LIGO/Virgo Event GW170817
    (IOP Publishing, 2018) Ajello, M.; Allafort, A.; Axelsson, M.; Baldini, L.; Barbiellini, G.; Baring, M.G.; Bastieri, D.; Bellazzini, R.; Berenji, B.; Bissaldi, E.; Blandford, R.D.; Bloom, E.D.; Bonino, R.; Bottacini, E.; Brandt, T.J.; Bregeon, J.; Bruel, P.; Buehler, R.; Burnett, T.H.; Buson, S.; Cameron, R.A.; Caputo, R.; Caraveo, P.A.; Casandjian, J.M.; Cavazzuti, E.; Chekhtman, A.; Cheung, C.C.; Chiang, J.; Chiaro, G.; Ciprini, S.; Cohen-Tanugi, J.; Cominsky, L.R.; Costantin, D.; Cuoco, A.; Cutini, S.; D’Ammando, F.; de Palma, F.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Dubois, R.; Dumora, D.; Favuzzi, C.; Ferrara, E.C.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Gill, R.; Giordano, F.; Giroletti, M.; Glanzman, T.; Granot, J.; Green, D.; Grenier, I.A.; Grondin, M.-H.; Guillemot, L.; Guiriec, S.; Harding, A.K.; Hays, E.; Horan, D.; Imazato, F.; Jóhannesson, G.; Kamae, T.; Kensei, S.; Kocevski, D.; Kuss, M.; La Mura, G.; Larsson, S.; Latronico, L.; Li, J.; Longo, F.; Loparco, F.; Lovellette, M.N.; Lubrano, P.; Magill, J.D.; Maldera, S.; Manfreda, A.; Mazziotta, M.N.; Michelson, P.F.; Mizuno, T.; Moiseev, A.A.; Monzani, M.E.; Moretti, E.; Morselli, A.; Moskalenko, I.V.; Negro, M.; Nuss, E.; Ojha, R.; Omodei, N.; Orlando, E.; Ormes, J.F.; Palatiello, M.; Paliya, V.S.; Paneque, D.; Persic, M.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Porter, T.A.; Principe, G.; Racusin, J.L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Ritz, S.; Rochester, L.S.; Ryde, F.; Parkinson, P.M. Saz; Sgrò, C.; Siskind, E.J.; Spada, F.; Spandre, G.; Spinelli, P.; Suson, D.J.; Tajima, H.; Takahashi, M.; Tak, D.; Thayer, J.G.; Thayer, J.B.; Torres, D.F.; Torresi, E.; Tosti, G.; Troja, E.; Valverde, J.; Venters, T.M.; Vianello, G.; Wood, K.; Yang, C.; Zaharijas, G.
    We present the Fermi Large Area Telescope (LAT) observations of the binary neutron star merger event GW170817 and the associated short gamma-ray burst (SGRB) GRB 170817A detected by the Fermi Gamma-ray Burst Monitor. The LAT was entering the South Atlantic Anomaly at the time of the LIGO/Virgo trigger (t GW) and therefore cannot place constraints on the existence of high-energy (E > 100 MeV) emission associated with the moment of binary coalescence. We focus instead on constraining high-energy emission on longer timescales. No candidate electromagnetic counterpart was detected by the LAT on timescales of minutes, hours, or days after the LIGO/Virgo detection. The resulting flux upper bound (at 95% C.L.) from the LAT is 4.5 × 10−10 erg cm−2 s−1 in the 0.1–1 GeV range covering a period from t GW + 1153 s to t GW + 2027 s. At the distance of GRB 170817A, this flux upper bound corresponds to a luminosity upper bound of 9.7 × 1043 erg s−1, which is five orders of magnitude less luminous than the only other LAT SGRB with known redshift, GRB 090510. We also discuss the prospects for LAT detection of electromagnetic counterparts to future gravitational-wave events from Advanced LIGO/Virgo in the context of GW170817/GRB 170817A.
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    Magnetic domain structures of focused ion beam-patterned cobalt films using scanning ion microscopy with polarization analysis
    (AIP Publishing LLC, 2004) Li, J.; Rau, C.; Rice Quantum Institute; Center for Nanoscience and Technology
    Studies of magnetic domain distributions in patterned magnetic materials are of pivotal importance in the areas of ultrahigh density magnetic recording, MRAM design, and miniaturized magnetic sensor arrays. Scanning ion microscopy with polarizationanalysis (SIMPA) is used to perform in situ topographic and magnetic domain imaging and focused ion beam(FIB) patterning. For FIB-patterned 30 nm thick Co films, it is found that rectangular Co bars of sizes between 10–30 μm exhibit S type, whereas circular shaped magnetic elements show C type micromagnetic magnetization patterns. It is shown that SIMPA provides a simple way to directly identify different micromagnetic domain patterns.
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    Searching the Gamma-Ray Sky for Counterparts to Gravitational Wave Sources: Fermi Gamma-Ray Burst Monitor and Large Area Telescope Observations of LVT151012 and GW151226
    (IOP, 2017) Racusin, J.L.; Burns, E.; Goldstein, A.; Connaughton, V.; Wilson-Hodge, C.A.; Jenke, P.; Blackburn, L.; Briggs, M.S.; Broida, J.; Camp, J.; Christensen, N.; Hui, C.M.; Littenberg, T.; Shawhan, P.; Singer, L.; Veitch, J.; Bhat, P.N.; Cleveland, W.; Fitzpatrick, G.; Gibby, M.H.; von Kienlin, A.; McBreen, S.; Mailyan, B.; Meegan, C.A.; Paciesas, W.S.; Preece, R.D.; Roberts, O.J.; Stanbro, M.; Veres, P.; Zhang, B.-B.; Fermi LAT Collaboration; Ackermann, M.; Albert, A.; Atwood, W.B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M.G.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Blandford, R.D.; Bloom, E.D.; Bonino, R.; Bregeon, J.; Bruel, P.; Buson, S.; Caliandro, G.A.; Cameron, R.A.; Caputo, R.; Caragiulo, M.; Caraveo, P.A.; Cavazzuti, E.; Charles, E.; Chiang, J.; Ciprini, S.; Costanza, F.; Cuoco, A.; Cutini, S.; D'Ammando, F.; de Palma, F.; Desiante, R.; Digel, S.W.; Di Lalla, N.; Di Mauro, M.; Di Venere, L.; Drell, P.S.; Favuzzi, C.; Ferrara, E.C.; Focke, W.B.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Gill, R.; Giroletti, M.; Glanzman, T.; Granot, J.; Green, D.; Grove, J.E.; Guillemot, L.; Guiriec, S.; Harding, A.K.; Jogler, T.; Jóhannesson, G.; Kamae, T.; Kensei, S.; Kocevski, D.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Longo, F.; Loparco, F.; Lubrano, P.; Magill, J.D.; Maldera, S.; Malyshev, D.; Mazziotta, M.N.; McEnery, J.E.; Michelson, P.F.; Mizuno, T.; Monzani, M.E.; Morselli, A.; Moskalenko, I.V.; Negro, M.; Nuss, E.; Omodei, N.; Orienti, M.; Orlando, E.; Ormes, J.F.; Paneque, D.; Perkins, J.S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T.A.; Principe, G.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Saz Parkinson, P.M.; Scargle, J.D.; Sgrò, C.; Simone, D.; Siskind, E.J.; Smith, D.A.; Spada, F.; Spinelli, P.; Suson, D.J.; Tajima, H.; Thayer, J.B.; Torres, D.F.; Troja, E.; Uchiyama, Y.; Vianello, G.; Wood, K.S.; Wood, M.
    We present the Fermi Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) observations of the LIGO binary black hole merger event GW151226 and candidate LVT151012. At the time of the LIGO triggers on LVT151012 and GW151226, GBM was observing 68% and 83% of the localization regions, and LAT was observing 47% and 32%, respectively. No candidate electromagnetic counterparts were detected by either the GBM or LAT. We present a detailed analysis of the GBM and LAT data over a range of timescales from seconds to years, using automated pipelines and new techniques for characterizing the flux upper bounds across large areas of the sky. Due to the partial GBM and LAT coverage of the large LIGO localization regions at the trigger times for both events, differences in source distances and masses, as well as the uncertain degree to which emission from these sources could be beamed, these non-detections cannot be used to constrain the variety of theoretical models recently applied to explain the candidate GBM counterpart to GW150914.
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    Three-Dimensional, Spin-Resolved Structure of Magnetic Vortex and Antivortex States in Patterned Co Films Using Scanning Ion Microscopy with Polarization Analysis
    (American Physical Society, 2006) Li, J.; Rau, C.; Rice Quantum Institute; Center for Nanoscience and Technology
    Scanning ion microscopy with polarization analysis is utilized for three-dimensional spin mapping of the surface magnetization (SM) of circular Co dots created inﾠsitu by focused ion beam etching of 30ﾠnm thin Co/Si(100) films. From 3D scanning ion microscopy with polarization analysis spin maps, direct evidence is found for the existence of vortex-antivortex states with in-plane circular or hyperbolic SM components and a wide core with perpendicular SM components which oscillate in the outer region and become zero.