Search

To optimize the beam loss and beam position along large accelerators systems and to determine the exposure of radiation sensitive components we developed several fiber optic dosimetry systems. Two systems are based on the radiation-induced attenuation which is independent of dose rate for the selected fiber. One of these systems is designed to monitor the radiation levels along the accelerator with a commercial Optical Time Domain Reflectometer (OTDR, distributed sensor). The resolution is limited to about 1 m. The second system consists of several local sensor spools the attenuation increase of which is measured with high precision optical power meters. Both systems allow the measurement of radiation doses up to 1000 Gy. The results are available every 5 minutes so that nearly real-time beam optimization is possible. Another system which is based on the induced Cerenkov light in a radiation hard optical fiber can trigger an accelerator shutdown within milli-seconds.

The proposal is divided into a main project and special projects. The main project consists of a service similar to the one given in the past to accelerator construction projects at CERN (ISR,SPS,LEP) on high-dose dosimetry, material irradiations, irradiations tests, standardization of test procedures and data compilations. Large experience in this field and numerous radiation damage test data of insulating and structural materials are available. The special projects cover three topics which are of specific interest for LHC detector physicists and engineers at CERN and in other high energy physics institutes, namely: Radiation effects in scintillators; Selection of radiation hard optical fibres for data transmission; and Selection and testing of radiation hard electronic components.

Surface seismic noise is often be the dominant component recorded during reverse vertical seismic profiling (RVSP). In the RVSP technique the seismic source is lowered into the wellbore while receivers are deployed on the surface. It is not uncommon that the desired direct and reflected seismic signals are several times below the background noise level. An adaptive noise filter is presented and applied to both synthetic and to real data. The filter is designed to suppress stationary harmonic noise as might be generated by reciprocating engines at a drill rig site. A finite difference algorithms is used to model both the seismic signals and the noise encountered in an RVSP environment. Real RVSP data are shown to demonstrate the effectiveness of the filter in removing harmonic background noise.