Experiments with Supersonic Beams as a Source of Cold Atoms

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Figure 4.29: A CAD image of the vacuum system of the 64 stage coilgun. The supersonic beam path is indicated by the red arrow. The chamber itself is a 6 inch OD stainless steel tube, configured with 8 inch Conflat flanges on either end. The chamber is pumped by a Varian 500 l/s turbomolecular pump, shown in blue, and the pressure is measured by a cold cathode ion gauge, shown in pink. The MCP feedthrough mounting flange is shown at the end of the coilgun in red, while the edge welded bellows translation stage is shown in yellow (without the aluminum translation stage support structure). The 3 50-pin D-Sub feedthroughs for the coil wires are mounted on an 8 inch blank, shown in green. The chamber itself is mounted to an aluminum support structure using the feet welded to the chamber shown in orange. Figure Courtesy Christian Parthey. either end of the vacuum system, allowing the support to be adjusted in 4 axes: x, y, pitch, and yaw. There is no need for the support mounting to have z or roll degrees of freedom. The coil support is aligned to the axis of the vacuum chamber using a telescope, and the same telescope is used to align the nozzle and skimmer to the coils. A cut-away CAD image of the support mounted in the vacuum chamber is shown in figure 4.28. The vacuum system of the coilgun chamber is shown in figure 4.29. The beam creation chamber which produces the supersonic beam of metastable neon atoms is unchanged from the proof-of-principle experiment, as are the nozzle operation pa- 103
ameters. The coilgun chamber consists of a 6 inch OD cylindrical stainless steel chamber, with 8 inch Conflat flanges on either end. The chamber is pumped by a Varian 551 l/s turbomolecular pump, shown in blue. The pump keeps the chamber at pressures below 1×10 −8 Torr, as measured by a cold cathode vacuum gauge (pink). As in the proof-of-principle experiment, the beam is detected after slowing by an MCP (feedthrough mount flange shown in red), which is mounted on a 50.8 mm translation stage (shown in yellow, without the translation stage support structure). The center of the first coil of the coilgun is located 555.7 mm from the exit of the nozzle, and ≈ 250mm from the base of the skimmer. The MCP is located 40.7mm (91.5mm) from the center of the of the last coil in the coilgun with the translation stage retracted (extended), and the distance from the nozzle to the MCP is 147.98 cm (153.06 cm). The beam is slowed enough to be resolved from the main peak directly at the end of the coilgun, so it is advantageous to have the detector as close as possible to the exit of the coils to avoid losing flux transversely. The electrical connections to the coils are made using an 8 inch Conflat blank, with 3 50-pin D-Sub feedthroughs from Accu-Glass welded in. The in-vacuum con- nectors are made from PEEK to ensure vacuum compatibility. Additionally, the wires running from the feedthroughs to the coils are bundled together and wrapped in a PEEK spiral to protect them. This also makes organizing the 64 pairs of wires some- what simpler. While the feedthroughs worked without a problem for several tens of thousands of pulses, they did eventually fail catastrophically (electrical failure, not loss of vacuum) without warning. The data shown in the following section is taken with the first set of feedthroughs. A higher isolation voltage set of feedthroughs was purchased (1 kV instead of 600 V), but these too eventually failed after several tens of thousands of shots, again without warning. Moving the coils out of vacuum became a priority for the 3rd generation coilgun described in chapter 5. 104
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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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Page 73 and 74: Chapter 4 The Atomic and Molecular
Page 75 and 76: field. In the L − S coupling regi
Page 77 and 78: 3 P2 E Figure 4.2: This graph gives
Page 79 and 80: For intermediate fields, the full p
Page 81 and 82: Figure 4.4: This figure illustrates
Page 83 and 84: The same effect is also responsible
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 91 and 92: the magnitude of the field some dis
Page 93 and 94: nozzle front surface aluminum catho
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
Page 111 and 112: 258V 1MΩ TTL 2.2mF 50Ω TTL 5V 5V
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: Figure 4.28: A cut-away CAD image o
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 and 130: 8 Ω LN2 Liquid Nitrogen Dewar Nozz
Page 131 and 132: Figure 4.33: Molecular oxygen slowi
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
Page 137 and 138: 10 mm 2.0 T 1.8 1.6 1.4 1.2 1.0 0.8
Page 139 and 140: 250V 1MΩ 3x 2.2mF TTL 5V feedback
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
Page 147 and 148: 4.1.3. In an anti-Helmholtz trap, t
Page 149 and 150: Figure 5.11: Photograph of the hydr
Page 151 and 152: Photodiode Signal (V) Time (s) Figu
Page 153 and 154: Figure 5.13: Time of flight plot of
Page 155 and 156: 500 l/s Turbo Pump Supersonic Nozzl
Page 157 and 158: Ionizer 500 l/s Turbo Pump Ion Opti
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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
Page 169 and 170: the electron g-factor which causes
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Figure 5.24: A schematic of the tel
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prevent the determination of the is
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(a) (b) time Figure 5.25: A 1D illu
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experiment, where a being is capabl
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potential position 2 x 243 nm Lα |
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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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