A Dyson Sphere is a hypothetical construct of a star purposely cloaked by a thick swarm of broken-up planetary material to better utilize all of the stellar energy. A clean Dyson Sphere identification would give a significant signature for intelligence at work. A search for Dyson Spheres has been carried out using the 250,000 source database of the IRAS infrared satellite which covered 96% of the sky. The search has used the Calgary database for the IRAS Low Resolution Spectrometer (LRS) to look for fits to blackbody spectra. Searches have been conducted for both pure (fully cloaked) and partial Dyson Spheres in the blackbody temperature region 100 ≤ T ≤ 600 ºK. When other stellar signatures that resemble a Dyson Sphere are used to eliminate sources that mimic Dyson Spheres very few candidates remain and even these are ambiguous. Upper limits are presented for both pure and partial Dyson Spheres. The sensitivity of the LRS was enough to find Dyson Spheres with the luminosity of the sun out to 300 pc, a reach that encompasses a million solar-type stars.

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Bent crystal channeling has promising advantages for accelerator beam collimation at high energy hadron facilities such as the LHC. This significance has been amplified by several surprising developments including multi-pass channeling and the observation of enhanced deflections over the entire arc of a bent crystal. The second effect has been observed both at RHIC and recently at the Tevatron. Results are reported showing channeling collimation of the circulating proton beam halo at the Tevatron. Parenthetically, this study is the highest energy proton channeling experiment ever carried out. The study is continuing.Keywords: Channeling, collimation, accelerator, Tevatron THE CHALLENGE OF COLLIDER COLLIMATIONDuring the design of the Superconducting Super Collider (SSC) it was recognized that collimating the intense proton beams required for high luminosity posed daunting challenges. A halo develops around any circulating beam due to many effects such as beam-gas and beam-beam interactions. Superconducting magnets can be quenched or destroyed if they scrape even a tiny portion of the beam. Collider detector devices such as silicon strip detectors are even more sensitive.In so-called single stage conventional collimation the beam halo is scraped by a collimator moved into the halo. Typically the collimator is a 1.5 m long block of steel or other medium or high-Z material. A certain fraction of the halo will survive, either by traversing the length of the collimator or by scattering out of the collimator block. Suppressing the out-scattered particles can be quite difficult. A more sophisticated way to handle the out-scattered particles is to go to a two-stage collimation system 1 . A thin primary target is used to scatter the beam out by increasing the amplitude of the betatron oscillations of the halo particles and thereby increasing the impact parameters on to secondary collimators during the next turns without influencing the unscattered beam.At the SSC, Mokhov and his colleagues 2 proposed an innovative solution to the collimation problem. In their arrangement an aligned, bent single crystal is used to deflect the beam out into a collimator much as a magnetic septum would. However, using the crystal results in a much higher deflection per unit length with little effective septum width. Since the SSC design there have been several developments that have made crystal collimation even more promising. One was a fuller understanding of so-called crystal multi-pass extraction first observed at CERN 3 . The other was the development of several approaches at the Institute for High Energy Physics (IHEP) and the Petersburg Nuclear Physics Institute (PNPI) for producing very short crystal bending lengths characteristically using anticlastic crystal deformations 4 . In view of the promise for both extraction and collimation the SSC sponsored a research program on crystal extraction at the Tevatron. That experiment, E853 5 , showed that extraction was possible in the context of a superconducting accelerator. FERMILA...

For the Crab pulsar (L = 10^^ erg/sec, ^ = 200 rad/ sec), Jc~ 1.7x10^^ particles/sec and e^^^ «2.8 xlO^^(J^/J) eV. Thus, for a given L, a larger flux of lower energy or smaller flux of higherenergy cosmic rays may be obtained, depending on J. In either case, 50% of the pulsar wave luminosity is converted into cosmic rays of energy less than Cj^^x-Within the superrelativistic approximation, these conclusions may be valid for the relativistic injection of neutral plasma of any composition, Care must be exercised in drawing far-reaching quantitative conclusions from our plane-wave model. Dependences on the azimuthal and polar angles in spherical geometry have been ignored. Furthermore, for a plane wave to be a good approximation, the radial excursion D of a particle during a half-period ?7 = TT, D = {TTC/Q)P/{^^ ~ 1), should be smaller than the radial scale length. This is only marginally satisfied at the injection radius and even less well at larger radii. Clearly, investigation of the spherical wave is called for.We acknowledge discussions with P. K.