Experiments with Supersonic Beams as a Source of Cold Atoms

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P1 P2 Valve Skimmer Reflected beam detector position P3 Direct beam detector position Triggering position Reflection position P4 25cm Figure 3.14: Illustration of rotor triggering and beam reflection positions. The motor servo controller delivers a TTL pulse to the data acquisition card when the rotor passes through the triggering position. The card then waits an empirically determined time before pulsing the Even-Lavie nozzle. The beam is illustrated in red and the vacuum pumps and detectors are indicated in the schematic. 45
TTL pulse to the data acquisition card when the rotor passes though the triggering position, which is 30 ◦ before the static reflection position. The card then waits an empirically determined time before pulsing the Even-Lavie nozzle to create the beam. This ensures that the beam will arrive at the nozzle at the correct time for the beam to be reflected to the slowed beam detector. The control program is capable of running the experiment at one shot per rotor rotation, but the vacuum pressure in the nozzle chamber rises too much when this is done at high rotor velocity. As such, the control system can be told to skip rotations, limiting the nozzle to a certain maximum repetition rate. 3.4 Data and Results Because the maximal rotation rate of the rotor is limited by vibrations to speeds well below the initial design parameters, as explained in section 3.3.2.2, it is necessary to reduce the speed of the helium beam below that obtained by cooling the nozzle to 77 K. At this temperature, a pure helium beam has a velocity of around 900 m/s. Even at the maximum rotation rate achieved of 60 Hz the rotor tip velocity is 190 m/s, which is not enough to significantly slow the beam. However, by mixing the helium with neon in a 50:50 mixture, the beam velocity is reduced to around 500−550m/s, depending on the backing pressure of the nozzle. Lowering the velocity of the incoming helium beam also has the advantage of improving the Debye-Waller factor, which should lead to a larger fraction of the helium being specularly reflected. The data described here is taken with the old spindle, limiting the rotor to 42 Hz and a tip velocity of 133 m/s. For the experiments and data described below, the specific gas mixture used is a 48:52 mixture of helium and neon, with a nozzle reservoir pressure of 42 psi. This mixture produces a helium beam with a velocity of 511 ± 9m/s. 46
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Copyright by Adam Alexander Libson
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General Methods of Controlling Atom
Page 5 and 6:
Acknowledgments First and foremost,
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to problems, and I frequently went
Page 9 and 10:
General Methods of Controlling Atom
Page 11 and 12: Table of Contents Acknowledgments v
Page 13 and 14: Chapter 5. Towards Trapping and Coo
Page 15 and 16: List of Figures 2.1 Comparison of e
Page 17 and 18: 5.12 Faraday Rotation Signal During
Page 19 and 20: producing a cold sample. Alternativ
Page 21 and 22: place inside a dilution refrigerato
Page 23 and 24: atoms or molecules are slowed using
Page 25 and 26: 2.1 Thermodynamics of Ideal Gases F
Page 27 and 28: Since there will be no heat exchang
Page 29 and 30: Using equation 2.17 to modify equat
Page 31 and 32: Normalized Effusive Beam Flux Norma
Page 33 and 34: general method for producing cold a
Page 35 and 36: The gas throughput of the nozzle ca
Page 37 and 38: Chapter 3 Slowing Supersonic Beams
Page 39 and 40: 3.1 Using Helium for Atom Optics Ex
Page 41 and 42: Figure 3.1: Calculated elastic scat
Page 43 and 44: that they can be prepared ex-situ a
Page 45 and 46: successful. Any water that remains
Page 47 and 48: Skimmer 300 l/s Turbo Pump Even-Lav
Page 49 and 50: Figure 3.5: A CAD image of the dete
Page 51 and 52: from tubular aluminum welded togeth
Page 53 and 54: Figure 3.7: A CAD image of the roto
Page 55 and 56: Figure 3.10: A CAD image of large c
Page 57 and 58: Figure 3.11: This plot shows the am
Page 59 and 60: approximations are made in this cal
Page 61: 3.3.3 Detection An SRS [61] residua
Page 65 and 66: A comparison of the time-of-flight
Page 67 and 68: eceding crystal. Each curve is the
Page 69 and 70: calculated slow beam velocity is qu
Page 71 and 72: the RGA does have an effect on the
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
Page 89 and 90: the coil can instead be switched be
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
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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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viability for molecules essential.
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8 Ω LN2 Liquid Nitrogen Dewar Nozz
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Figure 4.33: Molecular oxygen slowi
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Chapter 5 Towards Trapping and Cool
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Energy meV 0.05 0.00 0.05 0.0 0.2 0
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10 mm 2.0 T 1.8 1.6 1.4 1.2 1.0 0.8
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250V 1MΩ 3x 2.2mF TTL 5V feedback
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Magnetic Field (T) 1.9 1.7 1.5 1.3
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5.2.2.1 Principle of Operation of t
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Figure 5.8: Photograph of the trapp
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4.1.3. In an anti-Helmholtz trap, t
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Figure 5.11: Photograph of the hydr
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Photodiode Signal (V) Time (s) Figu
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Figure 5.13: Time of flight plot of
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500 l/s Turbo Pump Supersonic Nozzl
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Ionizer 500 l/s Turbo Pump Ion Opti
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guided the design of the apparatus.
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Z − Velocity (m/s) 100 60 30 0
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Atom Number 60 50 40 30 20 10 0.6 0
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scattered photon to extract informa
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where k1 · pi = − k2 · pi, wh
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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
Page 197 and 198:
[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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