We have used the SHIVA laser system to accelerate carbon disks to speeds in excess of 100 km/sec. The 3KJ/3 ns pulse, on a 1 mm diameter spot of a single disk produced a conventional shock of about 5 MB. The laser energy can, however, be stored in kinetic motion of this accelerated disk and delivered (reconverted to thermal energy) upon impact with another carbon disk. This collision occurs in a time much shorter than the 3 ns pulse, thus acting as a power amplifier. The shock pressures measured upon impact are estimated to be in the 20 MB range, thus demonstrating the amplification power of this colliding disk technique in creating ultra-high pressures. Theory and computer simulations of this process will be discussed, and compared with the experiment.

In this note, we consider how close we can come to the linac along the SLC arc during linac operation. In this case, radiation will come from beam striking a beam line component in the linac transport system. Radiation actually penetrating the shielding wall between the linac and the arc isn't considered since it will be orders of magnitude smaller than radiation which enters the arc through one of two openings in the shielding: (1) the opening through which the SLC beam transport components pass; and (2) a personnel accessway some fifty seven feet downbeam of the first opening. We make the assumption that with a little judicious placing of shielding small angle radiation can be eliminated, leaving only large angle radiation (e.g., 90/sup 0/) to enter the SLC arcs. The source then is essentially opposite either of the two openings. Because the personnel opening is further downbeam, it dominates the shielding requirements.