Planar laser induced fluorescence for temperature measurement of optical thermocavitation

Pulsed laser-induced cavitation, has been the subject of many studies describing bubble growth, collapse and ensuing shock waves. To a lesser extent, hydrodynamics of continuous wave (CW) cavitation or thermocavitation have also been reported. However, the temperature field around these bubbles has not been measured, partly because a sensor placed in the fluid would interfere with the bubble dynamics, but also because the short-lived bubble lifetimes (∼70–200 µs) demand high sampling rates which are costly to achieve via infrared (IR) imaging. Planar laser-induced fluorescence (PLIF) provides a non-intrusive alternative technique to costly IR imaging to measure the temperature around laser-induced cavitation bubbles. A 440 nm laser sheet excites rhodamine-B dye to fluoresce while thermocavitation is induced by a CW 810 nm laser. Post-calibration, the fluorescence intensity captured with a high-speed Phantom Miro camera is correlated to temperature field adjacent to the bubble. Using shadowgraphy and PLIF, a significant decrease in sensible heat is observed in the nucleation site– temperature decreases after bubble collapse and the initial heated volume of liquid shrinks. Based on irradiation time and temperature, the provided optical energy is estimated to be converted up to 50% into acoustic energy based on the bubble's size, with larger bubbles converting larger percentages

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Combined search for the quarks of a sequential fourth generation

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Soft material perforation via double-bubble laser-induced cavitation microjets

The resulting jet of two interacting laser-induced cavitation bubbles is optimized and studied as a technique for micro-scale targeting of soft materials. High controllability of double-bubble microjets can make such configurations favorable over single bubbles for applications where risk of ablation or thermal damage should be minimized such as in soft biological structures. In this study, double-bubble jets are directed toward an agar gel-based skin phantom to explore the application of micro-scale injection and toward a soft paraffin to quantify the targeting effectiveness of double-bubble over single-bubble jetting. The sharp elongation during the double-bubble process leads to fast, focused jets reaching average magnitudes of Ujet = 87.6 ± 9.9 m/s. When directed to agar, the penetration length and injected volume increase at ∼250 μm and 5 nl per subsequent jets. Such values are achieved without the use of fabricated micro-nozzles seen in existing needle-free laser injection systems. In soft paraffin, double-bubble jetting produces the same penetration length as single-bubble jetting, but with ∼45% reduction in damage area at a 3× greater target distance. Thus, double-bubble jetting can achieve smaller impact areas and greater target distances, potentially reducing collateral thermal damage and effects of strong shockwave pressures

Performance and Operation of the CMS Electromagnetic Calorimeter

The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Pairing and recombination features during meiosis in Cebus paraguayanus (Primates: Platyrrhini)

Background: Among neotropical Primates, the Cai monkey Cebus paraguayanus (CPA) presents long, conserved chromosome syntenies with the human karyotype (HSA) as well as numerous C+ blocks in different chromosome pairs. In this study, immunofluorescence (IF) against two proteins of the Synaptonemal Complex (SC), namely REC8 and SYCP1, two recombination protein markers (RPA and MLH1), and one protein involved in the pachytene checkpoint machinery (BRCA1) was performed in CPA spermatocytes in order to analyze chromosome meiotic behavior in detail. Results: Although in the vast majority of pachytene cells all autosomes were paired and synapsed, in a small number of nuclei the heterochromatic C-positive terminal region of bivalent 11 remained unpaired. The analysis of 75 CPA cells at pachytene revealed a mean of 43.22 MLH1 foci per nucleus and 1.07 MLH1 foci in each CPA bivalent 11, always positioned in the region homologous to HSA chromosome 21. Conclusion: Our results suggest that C blocks undergo delayed pairing and synapsis, although they do not interfere with the general progress of pairing and synapsis

Measurement of top quark–antiquark pair production in association with a W or Z boson in pp collisions at √s=8 TeV

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