Observation of multiple volume reflection of ultrarelativistic protons by a sequence of several bent silicon crystals.

The interactions of 400 GeV protons with different sequences of bent silicon crystals have been investigated at the H8 beam line of the CERN Super Proton Synchrotron. The multiple volume reflection of the proton beam has been studied in detail on a five-crystal reflector measuring an angular beam deflection theta = 52.96 +/- 0.14 microrad. The efficiency was found larger than 80% for an angular acceptance at the reflector entrance of 70 microrad, with a maximal efficiency value of epsilon = 0.90 +/- 0.01 +/- 0.03.

Melanoma of the choroid above the optic disc: considerations concerning a clinical case.

The authors report the case of a patient suffering from melanoma of the choroid above the optic disc. Given the good level of visual acuity and the location and extent of the damage, he was given a radiotherapy treatment with proton beams. At an interval of 6 months from this treatment, the neoformation appeared limited, and no vascular changes due to irradiation were observed.