Experiments with Supersonic Beams as a Source of Cold Atoms

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of an MCP, and thus will not be detected. However, the RGA used to detect helium in chapter 3 can also be used to detect molecular oxygen. The oxygen is ionized by electron impact and accelerated into a quadrupole which provides mass filtering. The ions are then detected with an electron multiplier. The RGA is mounted on the same translation stage as the MCP, which again permits measurement of the velocity of the beam. However, the ionization region of the RGA has some depth, as compared to the flat MCPm, which creates inherent uncertainty in the position of an oxygen molecule when it is ionized and subsequently detected. The distance from the end of the coilgun to the ionizer with the translation stage in the retracted(extended) position is 100 mm(150.8mm). 4.6.3 Oxygen Data and Results The results of the oxygen slowing are now presented. Using the oxygen-krypton mixture described above, and with the nozzle cooled to 150 K, the oxygen beam without any slowing has a velocity of 389 ± 5 m/s with a standard deviation of 28 m/s. This corresponds to a temperature of 3.0 K. This is significantly hotter that the previous beams described here. Clustering in the beam is the likely explanation of the increased beam temperature, as the valve is operated close to the condensation temperature of the krypton carrier gas. Time-of-flight profiles of the oxygen beam are presented in figure 4.33. The coilgun is operated at constant phase, where the phases used are between 47.8 ◦ and 63.2 ◦ . This corresponds to slowing of the beam to 242 m/s at the lowest phase, and to 83 m/s at the highest phase. For the 83 m/s beam, over 95% of the initial kinetic energy is removed. A full summary of the slowing results can be found in table 4.3. The time-of-flight profile in the graph on the right in figure 4.33 shows the entire beam, including the perturbed fast beam. As is clear from the figure, the 113
Figure 4.33: Molecular oxygen slowing data from the 64 stage coilgun. Each time-offlight curve is the average of 200 individual measurements. The slowed curves only show the slowed portion of the beam for clarity. The time of flight signal for a beam without firing the coils is shown in (a). The velocities of the beams shown on the left are (a) 389 m/s, (b) 242 m/s, (c) 195 m/s, (d) 155 m/s, (e) 114 m/s, and (f) 83 m/s. These results are summarized in table 4.3. The figure on the right shows the entire time of flight profile of the beam slowed to 114 m/s, including the perturbed initial beam. This shows how a portion of the initial beam is slowed, while the rest is relatively unchanged. Table 4.3: Final velocities (vf), simulated final velocities of the synchronous atom (vs), and coil phases, of the beams shown in figure 4.33. vf [m/s] vs [m/s] phase [degrees] (a) 389 ± 5 – – (b) 242 ± 13 243 47.8 ◦ (c) 195 ± 8 195 53.7 ◦ (d) 155 ± 5 156 57.7 ◦ (e) 114 ± 3 114 61.2 ◦ (f) 83 ± 3 84 63.2 ◦ 114
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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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Page 81 and 82: Figure 4.4: This figure illustrates
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Page 85 and 86: (a) (b) (c) Time Figure 4.5: A pict
Page 87 and 88: which the particles enter). The oth
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Page 95 and 96: Figure 4.9: A CAD overview of the s
Page 97 and 98: 258V 1MΩ 5V 1mF DC/DC Converter TT
Page 99 and 100: Figure 4.12: An oscilloscope trace
Page 101 and 102: (a) (b) Figure 4.14: A CAD image of
Page 103 and 104: -HV PS 4 M MCP Anode 10 M 1 M Trans
Page 105 and 106: Signal [V] 2.5 2.0 1.5 1.0 0.5 refe
Page 107 and 108: Figure 4.20: An exploded view of th
Page 109 and 110: (a) (b) (c) (e) Figure 4.21: A pict
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Page 113 and 114: closed. With the new thyristor gate
Page 115 and 116: HeNe M2 M1 BB /2 L BB PC coil PC PD
Page 117 and 118: Table 4.1: Peak magnetic fields mea
Page 119 and 120: Figure 4.28: A cut-away CAD image o
Page 121 and 122: ameters. The coilgun chamber consis
Page 123 and 124: Table 4.2: Final velocities (vf), s
Page 125 and 126: MCP Signal [arb. units] 2.0 1.5 (1)
Page 127 and 128: viability for molecules essential.
Page 129: 8 Ω LN2 Liquid Nitrogen Dewar Nozz
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Page 135 and 136: Energy meV 0.05 0.00 0.05 0.0 0.2 0
Page 137 and 138: 10 mm 2.0 T 1.8 1.6 1.4 1.2 1.0 0.8
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Page 141 and 142: Magnetic Field (T) 1.9 1.7 1.5 1.3
Page 143 and 144: 5.2.2.1 Principle of Operation of t
Page 145 and 146: Figure 5.8: Photograph of the trapp
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Page 151 and 152: Photodiode Signal (V) Time (s) Figu
Page 153 and 154: Figure 5.13: Time of flight plot of
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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
Page 173 and 174: prevent the determination of the is
Page 175 and 176: (a) (b) time Figure 5.25: A 1D illu
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Appendix 164
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y x V i Figure A.1: The geometry us
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Bibliography [1] H.J.MetcalfandP.va
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[17] Brian C. Sawyer, Benjamin L. L
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[34] R. Campargue. Progress in over
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[51] O. Carnal, M. Sigel, T. Sleato
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[70] Edvardas Narevicius, Adam Libs
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[87] Willis E. Lamb and Robert C. R
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[96] G.Gabrielse,N.S.Bowden,P.Oxley
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[110] N. Kolachevsky, J. Alnis, S.
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[125] Andreas Osterwalder, Samuel A
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[142] C. Cohen-Tannoudji, B. Diu, a
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[161] Paulo F. Bedaque, Aurel Bulga
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Experiments with Supersonic Beams as a Source of Cold Atoms

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