M. H. Van de Voorde

Results of Physical Tests on Polymer Materials at Cryogenic Temperatures

The mechanical and thermal properties of polymer materials have been studied in a temperature range from 4.2°K to 300°K. Some of these polymers have been irradiated up to 2 × 108 rad in liquid nitrogen and liquid neon and the same properties were subsequently tested. A brief description of the various testing techniques is given.

Effects of nuclear radiation on the optical properties of cerium-doped glass

Abstract Some twenty types of glass containing 0.5-4% CeO 2 have been irradiated in a 60 Co gamma cell and in the mixed neutron-gamma field of a nuclear reactor, at total integrated doses of up to 5 × 10 9 Rad (CH). The resulting colouration has been assessed quantitatively by measuring the light transmission with reference to air, in the range 360–510 nm. From the results, certain types of glass suitable for applications in nuclear engineering can be selected. Specifically, it was found that 1–2% CeO 2 content is usually sufficient to obtain radiation-resistant optical glass: the reduction in light transmission above 450 nm is nil at 10 8 Rad (CH), below 10% at 10 9 Rad (CH), and below 20% at 5 × 10 9 Rad (CH); the post-irradiation fading is negligible.

Radiation damage to electronic components

Abstract Characteristic properties are presented of some 40 different electronic components (resistors, capacitors, diodes, transistors, and integrated circuits) which were irradiated in a nuclear reactor up to 10 15 n/cm 2 ( E >1 MeV). Complete circuits (e.g. rf amplifiers and detectors, mixers, differential amplifiers, voltage-to-frequency converters, oscillators, power supplies) were irradiated near the CERN Intersecting Storage Rings up to 10 6 Rad (RPL) (dose measured with radiophotoluminescent dosimeters) under simulated operational conditions. Representative measured parameters, such as resistance, capacitance, forward voltage, reverse current, toggle frequencies, are given in graphs as a function of radiation dose. The results are discussed in detail and lead to the over-all conclusion that the operation of electronic components and circuits is seriously affected by radiation environments with doses in the order of 10 13 n/cm 2 or 10 4 Rad (RPL); some components and circuits fail completely at doses of 10 14 n/cm 2 or 10 5 Rad (RPL).

A comparison of the radiation damage of electronic components irradiated in different radiation fields

Abstract Resistors, capacitors, silicon diodes and transistors, TTL integrated circuits, and operational amplifiers have been irradiated in three different radiation environments: in a research reactor with up to 1015 n/cm2 (E>1 MeV), near a proton beam of the CERN Intersecting Storage Rings with up to 5 × 105 Rad, and with a 30 kCi 60Co gamma source with up to 1 × 107 Rad. Representative parameters, such as resistance, capacitance, forward voltage, reverse current, toggle frequencies, have been measured before and after irradiation. It was found that, in comparison with nuclear-reactor irradiations, the effect of 60Co gamma rays can be smaller by a factor of 100 or more, whereas high-dose-rate accelerator irradiation can be up to 5 times more damaging for the same nominal amount of irradiation. It is concluded that care has to be exercised when interpreting the results of radiation damage tests on electronic components in different radiation environments.

Results of physical tests on polymers at cryogenic temperatures

Abstract This paper describes the results of some physical tests conducted on polymeric materials used in the construction of superconducting magnets. A brief description of the various testing techniques is also given.

Radiation Resistance of Organic Materials at Cryo-Temperatures

The experimental procedures, the irradiation conditions and the radiation behaviour of a number of organic materials at liquid nitrogen temperature are reported.

High radiation dose luminescent and optical dosimetry systems

Abstract An investigation of the characteristics of radiophotoluminescent, thermoluminescent and optical absorption dosimeters has indicated that they are suitable for use as radiation damage dosimeters in high energy particle accelerators. An introduction is given to their respective modes of operation and to their integration into a practical dosimetry system.

Intercomparison of high-dose dosimeters in accelerator radiation fields

Abstract The radiation fields and dose rates produced by high energy proton beams directed on thick internal targets have been studied at the CERN 28 GeV/ c Proton Synchrotron. Description and intercomparison of the readings of 17 high-dose dosimeter systems are given.

Effects of neutron radiation on the electrical resistivity of copper at room temperature

Abstract Industrial, oxygen-free, high conductivity (OFHC) copper and electrolytic tough-pitch (ETP) copper have been irradiated to a total integrated neutron dose of about 5 × 10 19 n/cm 2 ( E >0.1 MeV) at 40°C. Resistance measurements have been made at 22°C before and after irradiation. The radiation-induced increase in the electrical resistivity at a dose of 1.5 × 10 19 n/cm was ∼ 5% for annealed OFHC and ∼3.5% for annealed ETP coppers, respectively.

Dose estimates outside the shielding of the CERN intersecting storage rings by the moyer method

Abstract Formulas and results are presented for a convenient estimation of dose levels outside the transverse shielding of a high-energy proton accelerator. They are obtained by applying the Moyer method to uniform, local, and exponential beam loss distributions. The techniques are used in shielding considerations of the CERN intersecting storage rings facility. The lay-out of the main shielding is described and estimates of the beam losses during various machine operations are summarized and used to evaluate doses outside the main shield.