25 results found
Burrows K, Hendricks RJ, Szymaniec K, et al., 2020, Measuring atom positions in a microwave cavity to evaluate distributed cavity phase shifts, METROLOGIA, Vol: 57, ISSN: 0026-1394
Beattie S, Jian B, Alcock J, et al., 2020, First accuracy evaluation of the NRC-FCs2 primary frequency standard, METROLOGIA, Vol: 57, ISSN: 0026-1394
Hendricks RJ, Ozimek F, Szymaniec K, et al., 2019, Cs Fountain Clocks for Commercial Realizations-An Improved and Robust Design, IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, Vol: 66, Pages: 624-631, ISSN: 0885-3010
Szymaniec K, Hendricks RJ, Turza K, et al., 2018, Operation of caesium fountain frequency standards with remote hydrogen maser references, METROLOGIA, Vol: 55, Pages: 782-788, ISSN: 0026-1394
Truppe S, Hambach M, Skoff S, et al., 2017, A buffer gas beam source for short, intense and slow molecular pulses, Journal of Modern Optics, Vol: 65, Pages: 246-254, ISSN: 0950-0340
Experiments with cold molecules usually begin with a molecular source. We describe the construction and characteristics of a cryogenic buff er gas source of CaF molecules. The source emits pulses with a typical duration of 240 μs, a mean speed of about 150 m/s, and a flux of 5x 10¹⁰ molecules per steradian per pulse in a single rotational state.
Tokunaga SK, Hendricks RJ, Tarbutt MR, et al., 2017, High-resolution mid-infrared spectroscopy of buffer-gas-cooled methyltrioxorhenium molecules, New Journal of Physics, Vol: 19, ISSN: 1367-2630
We demonstrate cryogenic buffer-gas cooling of gas-phase methyltrioxorhenium (MTO). This molecule is closely related to chiral organometallic molecules where the parity-violating energy differences between enantiomers is measurable. The molecules are produced with a rotational temperature of approximately 6 K by laser ablation of an MTO pellet inside a cryogenic helium buffer gas cell. Facilitated by the low temperature, we demonstrate absorption spectroscopy of the 10.2 μm antisymmetric Re=O stretching mode of MTO with a resolution of 8 MHz and a frequency accuracy of 30 MHz. We partially resolve the hyperfine structure and measure the nuclear quadrupole coupling of the excited vibrational state. Our ability to produce dense samples of complex molecules of this type at low temperatures represents a key step towards a precision measurement of parity violation in a chiral species.
Asselin P, Berger Y, Huet TR, et al., 2017, Characterising molecules for fundamental physics: an accurate spectroscopic model of methyltrioxorhenium derived from new infrared and millimetre-wave measurements, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 19, Pages: 4576-4587, ISSN: 1463-9076
Precise spectroscopic analysis of polyatomic molecules enables many striking advances in physical chemistry and fundamental physics. We use several new high-resolution spectroscopic devices to improve our understanding of the rotational and rovibrational structure of methyltrioxorhenium (MTO), the achiral parent of a family of large oxorhenium compounds that are ideal candidate species for a planned measurement of parity violation in chiral molecules. Using millimetre-wave and infrared spectroscopy in a pulsed supersonic jet, a cryogenic buffer gas cell, and room temperature absorption cells, we probe the ground state and the Re[double bond, length as m-dash]O antisymmetric and symmetric stretching excited states of both CH3187ReO3 and CH3185ReO3 isotopologues in the gas phase with unprecedented precision. By extending the rotational spectra to the 150–300 GHz range, we characterize the ground state rotational and hyperfine structure up to J = 43 and K = 41, resulting in refinements to the rotational, quartic and hyperfine parameters, and the determination of sextic parameters and a centrifugal distortion correction to the quadrupolar hyperfine constant. We obtain rovibrational data for temperatures between 6 and 300 K in the 970–1015 cm−1 range, at resolutions down to 8 MHz and accuracies of 30 MHz. We use these data to determine more precise excited-state rotational, Coriolis and quartic parameters, as well as the ground-state centrifugal distortion parameter DK of the 187Re isotopologue. We also account for hyperfine structure in the rovibrational transitions and hence determine the upper state rhenium atom quadrupole coupling constant eQq′.
Dunseith DP, Truppe S, Hendricks RJ, et al., 2015, A high quality, efficiently coupled microwave cavity for trapping cold molecules, Journal of Physics B - Atomic Molecular and Optical Physics, Vol: 48, ISSN: 0953-4075
Hendricks RJ, Holland DA, Truppe S, et al., 2014, Vibrational branching ratios and hyperfine structure of 11BH and its suitability for laser cooling, Frontiers in Physics, Vol: 2, ISSN: 2296-424X
The simple structure of the BH molecule makes it an excellent candidate for direct laser cooling. We measure the branching ratios for the decay of the A1Π (v′ = 0) state to vibrational levels of the ground state, X1Σ+, and find that they are exceedingly favorable for laser cooling. We verify that the branching ratio for the spin-forbidden transition to the intermediate a3Π state is inconsequentially small. We measure the frequency of the lowest rotational transition of the X state, and the hyperfine structure in the relevant levels of both the X and A states, and determine the nuclear electric quadrupole and magnetic dipole coupling constants. Our results show that, with a relatively simple laser cooling scheme, a Zeeman slower and magneto-optical trap can be used to cool, slow and trap BH molecules.
Truppe S, Hendricks RJ, Tokunaga SK, et al., 2014, Microwave spectroscopy of A-doublet transitions in the ground state of CH, JOURNAL OF MOLECULAR SPECTROSCOPY, Vol: 300, Pages: 70-78, ISSN: 0022-2852
Truppe S, Hendricks RJ, Hinds EA, et al., 2013, Measurement of the lowest millimeter-wave transition frequency of the CH radical, Astrophysical Journal, Vol: 780, ISSN: 1538-4357
The CH radical offers a sensitive way to test the hypothesis that fundamental constants measured on earth may differ from those observed in other parts of the universe. The starting point for such a comparison is to have accurate laboratory frequencies. Here, we measure the frequency of the lowest millimeter-wave transition of CH, near 535 GHz, with an accuracy of 0.6 kHz. This improves the uncertainty by roughly two orders of magnitude over previous determinations and opens the way for sensitive new tests of varying constants.
Truppe S, Hendricks RJ, Tokunaga SK, et al., 2013, A search for varying fundamental constants using hertz-level frequency measurements of cold CH molecules, Nature Communications, Vol: 4, ISSN: 2041-1723
Many modern theories predict that the fundamental constants depend on time, position or the local density of matter. Here we develop a spectroscopic method for pulsed beams of cold molecules, and use it to measure the frequencies of microwave transitions in CH with accuracy down to 3 Hz. By comparing these frequencies with those measured from sources of CH in the Milky Way, we test the hypothesis that fundamental constants may differ between the high- and low-density environments of the Earth and the interstellar medium. For the fine structure constant we find Δα/α=(0.3±1.1) × 10−7, the strongest limit to date on such a variation of α. For the electron-to-proton mass ratio we find Δμ/μ=(−0.7±2.2) × 10−7. We suggest how dedicated astrophysical measurements can improve these constraints further and can also constrain temporal variation of the constants.
Bulleid NE, Skoff SM, Hendricks RJ, et al., 2013, Characterization of a cryogenic beam source for atoms and molecules, Phys. Chem. Chem. Phys.
Bulleid NE, Hendricks RJ, Hinds EA, et al., 2012, Traveling-wave deceleration of heavy polar molecules in low-field-seeking states, PHYSICAL REVIEW A, Vol: 86, ISSN: 1050-2947
Skoff SM, Hendricks RJ, Sinclair CDJ, et al., 2011, Diffusion, thermalization, and optical pumping of YbF molecules in a cold buffer-gas cell, PHYSICAL REVIEW A, Vol: 83, ISSN: 1050-2947
Zhuang X, Le A, Steimle TC, et al., 2011, Franck-Condon factors and radiative lifetime of the A(2)Pi(1/2)-X-2 Sigma(+) transition of ytterbium monofluoride, YbF, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 13, Pages: 19013-19017, ISSN: 1463-9076
Skoff SM, Hendricks RJ, Sinclair CDJ, et al., 2009, Doppler-free laser spectroscopy of buffer-gas-cooled molecular radicals, NEW JOURNAL OF PHYSICS, Vol: 11, ISSN: 1367-2630
Poschinger UG, Huber G, Ziesel F, et al., 2009, Coherent manipulation of a Ca-40(+) spin qubit in a micro ion trap, JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, Vol: 42, ISSN: 0953-4075
Phillips ES, Hendricks RJ, Abdulla AM, et al., 2008, Dynamics of axialized laser-cooled ions in a Penning trap, PHYSICAL REVIEW A, Vol: 78, ISSN: 1050-2947
Hendricks RJ, Phillips ES, Segal DM, et al., 2008, Laser cooling in the Penning trap: an analytical model for cooling rates in the presence of an axializing field, JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, Vol: 41, ISSN: 0953-4075
Hendricks RJ, Sorensen JL, Champenois C, et al., 2008, Doppler cooling of calcium ions using a dipole-forbidden transition, PHYSICAL REVIEW A, Vol: 77, ISSN: 1050-2947
Champenois C, Hagel G, Knoop M, et al., 2008, Two photon Doppler cooling of atoms with an intermediate metastable state
Atomic clock performances are limited by the fluctuations of the local oscillator frequency. During an atomic clock operation, only a fraction of the cycle time is devoted to the excitation of the clock transition, limiting the sensitivity to these fluctuations and thus the ability to correct them. The rest of the time is needed to detect the probability of transition to the clock excited state or, for example, to cool the atoms to temperatures compatible with the required precision. A key issue to reach high clock stability is to reduce these dead times. We propose a laser excitation scheme that could shorten the laser cooling time and the detection time for some of the atomic species proposed as frequency standards in the optical domain like Ca+, Sr+, Ca, Sr and Yb.
Hendricks RJ, Grant DM, Herskind PF, et al., 2007, An all-optical ion-loading technique for scalable microtrap architectures
Hendricks RJ, Grant DM, Herskind PF, et al., 2007, An all-optical ion-loading technique for scalable microtrap architectures, APPLIED PHYSICS B-LASERS AND OPTICS, Vol: 88, Pages: 507-513, ISSN: 0946-2171
Hendricks R, 2000, CERN opens antimatter factory, Physics World, Vol: 13, ISSN: 0953-8585
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