Physics Commons^™

The Upscattering Of Ultracold Neutrons From The Polymer (C6h12)N, Eduard I. Sharapov, Christopher L. Morris, Mark Makela, Andy Saunders, Evan R. Adamek, Leah J. Broussard, Chris B. Cude-Woods, Deion E. Fellers, Peter Geltenbort, Monika Hartl, Siraj I. Hasan, Kevin P. Hickerson, Gary E. Hogan, Anthony T. Holley, C. M. Lavelle, Chen-Yu Liu, Michael P. Mendenhall, Jose Ortiz, Robert W. Pattie, David G. Phillips, John Ramsey, Daniel J. Salvat, Susan J. Seestrom, Erik Shaw, Sky Sjue, Walter E. Sondheim, Brittany Vorndick, Zhehui Wang, Tanner L. Womack, Andrew R. Young, B. A. Zeck

Robert W. Pattie Jr.

All-Optical Control Of Electron Trapping In Plasma Channels, Serguei Y. Kalmykov, Bradley A. Shadwick, Xavier Davoine

Serge Youri Kalmykov

The accelerating bucket of a laser-plasma accelerator (a cavity of electron density maintained by the laser pulse radiation pressure) evolves slowly, in lock-step with the optical driver, and readily traps background electrons. The trapping process can thus be controlled by purely optical means. Sharp gradients in the nonlinear refractive index produce a large frequency red-shift, localized at the leading edge of the pulse. Negative group velocity dispersion associated with the plasma response compresses the laser pulse into a relativistic optical shock (ROS), slowing the pulse (and the bucket), reducing the electron dephasing length, and limiting energy gain. Even more importantly, …

Measurements Of Ultracold Neutron Upscattering And Absorption In Polyethylene And Vanadium, Eduard I. Sharapov, Charles L. Morris, Mark Makela, Andy Saunders, Evan R. Adamek, Yelena Bagdasarova, Leah J. Broussard, Chris Cude-Woods, Deon E. Fellers, Peter Geltenbort, Siraj I. Hasan, Kevin P. Hickerson, Gary Hogan, Anthony T. Holley, Chen-Yu Liu, Michael P. Mendenhall, Jose Ortiz, Robert W. Pattie Jr., David G. Phillips, John Ramsey, D. J. Salvat, Susan J. Seestrom, E. Shaw, Sky Sjue, Walter E. Sondheim, Brittany Vorndick, Zhehui Wang, Tanner L. Womack, Andrew R. Young, B. A. Zeck

Robert W. Pattie Jr.

Near-Unity Nuclear Polarization With An Open-Source 129xe Hyperpolarizer For Nmr And Mri, Panayiotis Nikolaou, Aaron M. Coffey, Laura L. Walkup, Brogan M. Gust, Nicholas Whiting, Hayley Newton, Scott Barcus, Iga Muradyan, Mikayel Dabaghyan, Gregory D. Moroz, Matthew S. Rosen, Samuel Patz, Michael J. Barlow, Eduard Y. Chekmenev, Boyd M. Goodson

Nicholas Whiting

Interaction Of Ultrashort-Laser Pulses With Induced Undercritical Plasmas In Fused Silica, Jeremy Gulley, Sebastian Winkler, William Dennis, Carl Liebig, Razvan Stoian

Jeremy R. Gulley

Ultrafast light-material interactions near the damage threshold are often studied using postmortem analysis of damaged dielectric materials. Corresponding simulations of ultrashort pulse propagation through the material are frequently used to gain additional insight into the processes leading to such damage. However, comparison between such experimental and numerical results is often qualitative, and pulses near to but not exceeding the damage threshold leave no permanent changes in the material for postmortem analysis. In this article, a series of experiments is presented that measures the near- and far-field properties of a 140-fs laser pulse after propagation through a fused silica sample in …

High Precision K-Shell Photoabsorption Cross Sections For Atomic Oxygen: Experiment And Theory, Brendan M. Mclaughlin, C P. Ballance, K P. Bowen, D J. Gardenghi, Wayne C. Stolte

Wayne C. Stolte

Photoabsorption of atomic oxygen in the energy region below the 1s −1 threshold in X-ray spectroscopy from Chandra and XMM-Newton is observed in a variety of X-ray binary spectra. Photoabsorption cross sections determined from an R-matrix method with pseudo-states and new, high precision measurements from the Advanced Light Source (ALS) are presented. High-resolution spectroscopy with E/ΔE ≈ 4250 ± 400 was obtained for photon energies from 520 eV to 555 eV at an energy resolution of 124 ± 12 meV FWHM. K-shell photoabsorption cross section measurements were made with a re-analysis of previous experimental data on atomic oxygen at the …

780 Nm Diode Lasers For Atomic Physics, Bryson Vivas, Simone Carpenter, Jenny Novak, Andrew M. C. Dawes

Andrew M C Dawes

This poster presents the results of the summer research project conducted by Bryson Vivas, Simone Carpenter, and Jenny Novak. The research was supervised by Dr. Andrew Dawes and conducted in the Photonics and Quantum Optics Lab of Pacific University.

Simultaneous Quantum-State Measurements Using Array Detection, Andrew Dawes, Mark Beck

Andrew M C Dawes

We have simultaneously measured the quantum states of two different spatial modes of the same optical beam by performing quantum-state tomography with an array detector. Both modes are well described by coherent states, but the projection of the signal onto the local oscillator mode contains a mean of 0.09 photons, while a more complicated mode has a mean of 4.3 photons. This demonstrates that for this particular mode the effective detection efficiency when using array detection is over 40 times greater than when using single detectors.

Mode Optimization For Quantum-State Tomography With Array Detectors, Andrew M. Dawes, Mark Beck, K. Banaszek

Andrew M C Dawes

We demonstrate that it is possible to choose an optimal signal mode for state reconstruction when performing quantum-state tomography with array detectors. The mode optimization is done during the data analysis ~i.e., after all the data have been collected.! We develop theoretically a procedure for finding the mode that satisfies a criterion which is quadratic in field operators; as examples we explicitly show how to maximize the average photon number, or the amount of quadrature squeezing. We experimentally demonstrate the technique by finding the mode which maximizes the average photon number for coherent-state signal beams occupying both linear and sinusoidal …

Optical Switching With Cold Atoms, Andrew Dawes

Andrew M C Dawes

A Viewpoint on: Efficient All-Optical Switching Using Slow Light within a Hollow Fiber M. Bajcsy, S. Hofferberth, V. Balic, T. Peyronel, M. Hafezi, A. S. Zibrov, V. Vuletic, and M. D. Lukin Phys. Rev. Lett. 102, 203902 (2009) – Published May 18, 2009

Precision Measurement Of The Neutron Beta-Decay Asymmetry, Michael P. Mendenhall, Robert W. Pattie, Yelena Bagdasarova, David B. Berguno, Leah J. Broussard, Richard Carr, Scott Currie, Xinjian Ding, Bradley W. Filippone, Alejandro Garcia, Peter Geltenbort, Kevin P. Hickerson, J. Todd Hoagland, Anthony T. Holley, Ran Hong, Takeyasu M. Ito, Andreas Knecht, Chenyu Liu, J. L. Liu, Mark Makela, Russell R. Mammei, J. W. Martin, Dan Melconian, Spencer D. Moore, Christopher L. Morris, Margaret L. Pitt, Blakely Plaster, John C. Ramsey, Roger Rios, Andy Saunders, Susan J. Seestrom, Eduard I. Sharapov, Walter E. Sondheim, E. Tatar, Robert B. Vogelaar, Brittany Vorndick, Christopher Wrede, Andrew R. Young, B. A. Zeck

Robert W. Pattie Jr.

Measurements Of Nh3 Linestrengths And Collisional Broadening Coefficients In N2, O2, Co2, And H2o Near 1103.46 Cm−1, Kyle Owen, Et-Touhami Es-Sebbar, Aamir Farooq

Dr. Et-touhami Es-sebbar

Laser-based ammonia gas sensors have useful applications in many fields including combustion, atmospheric monitoring, and medical diagnostics. Calibration-free trace gas sensors require the spectroscopic parameters including linestrengths and collisional broadening coefficients to be known. Ammonia's strong ν2 vibrational band between View the MathML source has the high absorption strength needed for sensing small concentrations. Within this band, the 1103.46 cm−1 feature is one of the strongest and has minimal interference from CO2 and H2O. However, the six rotational transitions that make up this feature have not been studied previously with absorption spectroscopy due to their small line spacing ranging from …

Effects Of N2o And O2 Addition To Nitrogen Townsend Dielectric Barrier Discharges At Atmospheric Pressure On The Absolute Ground-State Atomic Nitrogen Density, Et. Es-Sebbar, N. Gherardi, F. Massines

Dr. Et-touhami Es-sebbar

Absolute ground-state density of nitrogen atoms N (2p3 4S3/2) in non-equilibrium Townsend dielectric barrier discharges (TDBDs) at atmospheric pressure sustained in N2/N2O and N2/O2 gas mixtures has been measured using Two-photon absorption laser-induced fluorescence (TALIF) spectroscopy. The quantitative measurements have been obtained by TALIF calibration using krypton as a reference gas. We previously reported that the maximum of N (2p3 4S3/2) atom density is around 3 × 1014 cm−3 in pure nitrogen TDBD, and that this maximum depends strongly on the mean energy dissipated in the gas. In the two gas mixtures studied here, results show that the absolute N …

Temperature-Dependent Absorption Cross-Section Measurements Of 1-Butene (1-C4h8) In Vuv And Ir, Et-Touhami Es-Sebbar, Yves Benilan, Aamir Farooq

Dr. Et-touhami Es-sebbar

Vacuum ultraviolet (VUV) and infrared (IR) absorption cross-section measurements of 1-butene (1-C4H8; CH2=CHCH2CH3; Butylene) are reported over the temperature range of 296–529 K. The VUV measurements are performed between 115 and 205 nm using synchrotron radiation as a tunable VUV light source. Fourier Transform Infrared (FTIR) spectroscopy is employed to measure absorption cross-section and band strengths in the IR region between 1.54 and 25 μm (∼6500–400 cm−1). The measured room-temperature VUV and IR absorption cross-sections are compared with available literature data and are found to be in good agreement. The oscillator strength for the electronic transition (A1A′→X1A′) around 150–205 nm …

Syllabus_Lecture_Notes_Collective_Phenomena_In_Laser_Plasmas_Phy998_2_Fall_2013, Serge Y. Kalmykov

Serge Youri Kalmykov

Interaction of high-power laser radiation with rarefied, fully ionized plasmas is rich in nonlinear collective phenomena. It is essentially three-dimensional and is dominated by the excitation of various modes of plasma oscillations, most important of which are electron Langmuir waves. These waves may trap externally injected electrons or initially quiescent plasma electrons, accelerating them to GeV-scale energies. Laser pulses can also launch collisionless shocks, which may accelerate plasma ions to MeV energies. Furthermore, relativistic mass effect and electron density perturbations by the radiation pressure cause laser pulse self-focusing and filamentation, leading to the radiation pulse self-guiding over many Rayleigh lengths. …