Cooling collimation

Figure 9. View of the essential parts of the crossed beam apparatus using short-lived radioactive labeling and detection (23) Ay radioactive beam source By scrubber-furnace C, LN -cooled collimator D, shut-off plug Ey nozzle beam furnace and cryopump F, gate valve G, hodoscope H, LN -coohd beam trap 7, calibrated beam monitor /, silicon surface barrier detectors K, halogen crossed beam L, radioactive beam M, rotary feed-through used to close the source stopcock.

Fig. 4 Left-hand side cartoon of the water-cooled collimator-target-recoil chamber-beam stop assembly as used for experiments described in [41-43] (red arrow—incoming beam). Right-hand side Results of a finite element calculation of the thermal load in the Ti vacuum window...

Optothemial spectroscopy is a bolonietric method that monitors the energy in a stream of molecules rather than in the light beam. A well collimated molecular beam is directed toward a liquid helium cooled bolometer. There will be energy... 

The intensity of the He beam of the apparatus shown in Fig. 5 collimated to 0.4° full width at half maximum (FWHM) is typically 1010 singlets/sec (or 3 -1014 atoms/sec sr) and 1.5 -109 triplets/sec for beam energies of 66 to 350 meV and about 20% of this value at 16.5 meV (liquid-nitrogen-cooled nozzle). The triplet intensity can be increased at the expense of a poorer velocity resolution by a lower electron-acceleration voltage. 

Figure 6.10 An example of a recirculating straight open-channel design flume. The components are a = head box, b = collimator, c = open channel, d = weir, e = tail box, f = motor, g = axial pump, h = return pipe and cooling coil, and i = electric jacks. (Modified from Khalili et al., 2001.)...

The helium ion beam was first collimated by means of the water-cooled copper and graphite collimater A. The second collimator B reduced the beam to the required size. The stainless steel holder C supported a 0.04-cm thick duraluminum foil which sealed the rest of the probe assembly from the cyclotron vacuum. Aluminum absorber strips could be mounted behind this foil to decrease the beam energy. Holder D supported the target. Foils C and D were cooled by rapid circulation of helium between them. 

Choice of moderator depends on the application of the positron beam. For implantation defect spectroscopy the priority is to maximise moderator efficiency, whereas for electrostatic systems a well-collimated parallel beam requires a planar low-(f + surface cooled to minimise thermal smearing. 

Using modern techniques of laser cooling, high-intensity beams of metastable He (ls2s S) atoms can be prepared well suited for precision spectroscopy in high electric fields [7]. After transversal cooling, well collimated beams can be exposed... 

The x-ray tube assembly is a simple and maintenance-free device. However, the overall efficiency of an x-ray tube is very low - approximately 1% or less. Most of the energy supplied to the tube is converted into heat, and therefore, the anode must be continuously cooled with chilled water to avoid target meltdown. The input power to the sealed x-ray tube ( 0.5 to 3 kW) is therefore, limited by the tube s ability to dissipate heat, but the resultant energy of the usable x-ray beam is much lower than 1% of the input power because only a small fraction of the generated photons exits through each window. Additional losses occur during the monochromatization and collimation of the beam (see section 2.3). 

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