Experiments with Supersonic Beams as a Source of Cold Atoms

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The one drawback of the above implementations of single-photon cooling is that the cooling only operates in one dimension, and cooling in more than one dimension requires trap ergodicity or collisions between the atoms to provide mixing of the degrees of freedom. Cooling in three dimensions requires the one-way wall and the new trapping potential to form a shell around the trap the atoms are initially held in. While this is not practical with an optical potential, it is possible to create these potentials using static and radio frequency (RF) or microwave magnetic fields. The RF field couples the internal states of the atom and shifts their energies [142, 143], which can create a conservative potential. The atoms are considered to be “dressed” by the RF photons, and the resulting states are referred to as “RF-dressed states”. RF-dressed potentials have been proposed [144] and demonstrated [145] for trapping of neutral atoms, and have permitted the creation of novel trap geometries [146–148]. The effect on the trapped atoms of the interaction between the RF field and the trap has been analyzed in detail [149–151]. Single-photon cooling of atoms and molecules using population transfer between RF-dressed states of a magnetic trap was first considered and proposed in [152]. It is this technique which will be adapted for use with hydrogen isotopes, though the current trap will need to be changed to one with a bias field, such as a Ioffe-Pritchard magnetic trap [153]. An illustration of the proposed implementation of RF-dressed single-photon cooling for atomic hydrogen isotopes is shown in figure 5.26. For simplicity, only two states of the 1S manifold are considered in the following discussion. Atoms which are in the lower dressed state (labeled |−〉 in figure 5.26) are low-field-seeking at low magnetic field, and high-field-seeking at high magnetic field, with the field strength of the cross-over in behavior defined by the frequency of the RF magnetic field. Similarly, atoms in the upper dressed state(labeled |+〉) are high-field-seeking at low field, and low-field-seeking at high field, with the shift in behavior occuring 161
potential position 2 x 243 nm Lα |+> |-> 2S, 2P Figure 5.26: A scheme for implementing RF-dressed single-photon cooling of atomic hydrogen isotopes in the high field limit. Two of the four levels of the 1S manifold are depicted, labeled |+〉 and |−〉. These levels are coupled by RF magnetic fields, which shift the “bare” states and create avoided crossings. Atoms which are originally trapped in the |−〉 state are excited to the 2S level at their classical turning point using a two photon transition at 243 nm. Stark mixing of the 2S and 2P states causes the atoms to quickly decay via spontaneous emission of a Lyman α photon. The atoms that decay into the |+〉 state are trapped with nearly zero kinetic energy, with the probablitiy of reaching the |+〉 state determined by the branching ratio. 162 1S
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Copyright by Adam Alexander Libson
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General Methods of Controlling Atom
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Acknowledgments First and foremost,
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to problems, and I frequently went
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General Methods of Controlling Atom
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Table of Contents Acknowledgments v
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Chapter 5. Towards Trapping and Coo
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List of Figures 2.1 Comparison of e
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5.12 Faraday Rotation Signal During
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producing a cold sample. Alternativ
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place inside a dilution refrigerato
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atoms or molecules are slowed using
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2.1 Thermodynamics of Ideal Gases F
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Since there will be no heat exchang
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Using equation 2.17 to modify equat
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Normalized Effusive Beam Flux Norma
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general method for producing cold a
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The gas throughput of the nozzle ca
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Chapter 3 Slowing Supersonic Beams
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3.1 Using Helium for Atom Optics Ex
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Figure 3.1: Calculated elastic scat
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that they can be prepared ex-situ a
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successful. Any water that remains
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Skimmer 300 l/s Turbo Pump Even-Lav
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Figure 3.5: A CAD image of the dete
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from tubular aluminum welded togeth
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Figure 3.7: A CAD image of the roto
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Figure 3.10: A CAD image of large c
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Figure 3.11: This plot shows the am
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approximations are made in this cal
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3.3.3 Detection An SRS [61] residua
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TTL pulse to the data acquisition c
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A comparison of the time-of-flight
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eceding crystal. Each curve is the
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calculated slow beam velocity is qu
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the RGA does have an effect on the
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Chapter 4 The Atomic and Molecular
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field. In the L − S coupling regi
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3 P2 E Figure 4.2: This graph gives
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For intermediate fields, the full p
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Figure 4.4: This figure illustrates
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The same effect is also responsible
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(a) (b) (c) Time Figure 4.5: A pict
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which the particles enter). The oth
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the coil can instead be switched be
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the magnitude of the field some dis
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nozzle front surface aluminum catho
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Figure 4.9: A CAD overview of the s
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258V 1MΩ 5V 1mF DC/DC Converter TT
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Figure 4.12: An oscilloscope trace
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(a) (b) Figure 4.14: A CAD image of
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-HV PS 4 M MCP Anode 10 M 1 M Trans
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Signal [V] 2.5 2.0 1.5 1.0 0.5 refe
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Figure 4.20: An exploded view of th
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(a) (b) (c) (e) Figure 4.21: A pict
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258V 1MΩ TTL 2.2mF 50Ω TTL 5V 5V
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closed. With the new thyristor gate
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HeNe M2 M1 BB /2 L BB PC coil PC PD
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Table 4.1: Peak magnetic fields mea
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Figure 4.28: A cut-away CAD image o
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ameters. The coilgun chamber consis
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Table 4.2: Final velocities (vf), s
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MCP Signal [arb. units] 2.0 1.5 (1)
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Page 129 and 130: 8 Ω LN2 Liquid Nitrogen Dewar Nozz
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Page 133 and 134: Chapter 5 Towards Trapping and Cool
Page 135 and 136: Energy meV 0.05 0.00 0.05 0.0 0.2 0
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Page 139 and 140: 250V 1MΩ 3x 2.2mF TTL 5V feedback
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Page 145 and 146: Figure 5.8: Photograph of the trapp
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Page 149 and 150: Figure 5.11: Photograph of the hydr
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Page 157 and 158: Ionizer 500 l/s Turbo Pump Ion Opti
Page 159 and 160: guided the design of the apparatus.
Page 161 and 162: Z − Velocity (m/s) 100 60 30 0
Page 163 and 164: Atom Number 60 50 40 30 20 10 0.6 0
Page 165 and 166: scattered photon to extract informa
Page 167 and 168: where k1 · pi = − k2 · pi, wh
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Page 171 and 172: Figure 5.24: A schematic of the tel
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Page 175 and 176: (a) (b) time Figure 5.25: A 1D illu
Page 177: experiment, where a being is capabl
Page 181 and 182: Appendix 164
Page 183 and 184: y x V i Figure A.1: The geometry us
Page 185 and 186: Bibliography [1] H.J.MetcalfandP.va
Page 187 and 188: [17] Brian C. Sawyer, Benjamin L. L
Page 189 and 190: [34] R. Campargue. Progress in over
Page 191 and 192: [51] O. Carnal, M. Sigel, T. Sleato
Page 193 and 194: [70] Edvardas Narevicius, Adam Libs
Page 195 and 196: [87] Willis E. Lamb and Robert C. R
Page 197 and 198: [96] G.Gabrielse,N.S.Bowden,P.Oxley
Page 199 and 200: [110] N. Kolachevsky, J. Alnis, S.
Page 201 and 202: [125] Andreas Osterwalder, Samuel A
Page 203 and 204: [142] C. Cohen-Tannoudji, B. Diu, a
Page 205 and 206: [161] Paulo F. Bedaque, Aurel Bulga
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Experiments with Supersonic Beams as a Source of Cold Atoms

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