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LiF thermoluminescent dosimeters are more accurate than film badges for personnel monitoring in locations where the quality of X-ray or gamma radiation ranges from soft to hard (e.g. plutonium refining areas). l'herefore, thermoluminescent dosimeters were added to the film badges of sixty-six employees assigned to a plutonium finishing area at the Savannah River Plant to assist in the interpretation of low-energy gamma radiation exposure. During the first 6 months of 1966, the skin exposure measured by thermoluminescent dosimeters averaged one-half of that measured by the film badges.A second LiF dosimeter with copper and polyethylene filters added to the film badges of the same personnel showed that the low-energy photons also caused a similar error in the measurement of penetrating radiation exposure by the film badge.Observed differences between the LiF and film dosimetry results were reproduced under controlled conditions by giving film badges and thermoluminescent dosimeters known exposures of X-ray and gamma radiation. LiF results were within 20% of the measured exposures; however, at 48 keV the film interpretation of skin dose was high by a factor of 2.0, and at 105 keV the film interpretation was high by a factor of 2.7 for the skin dose and 2.0 for the penctrating dose.LITHIUM fluoride (LiF) thermoluminescent dosimeters are being developed at the Savannah River Laboratory (SRL) to supplement and possibly replace film badges. The many limitations inherent in a film dosimetry system are well known to the health physicist. Errors introduced by the energy dependence of film can be minimized when the energy of the exposing gamma or X-radiation is known and a source of the same energy is used to calibrate the film. However, it is difficult, and at times impossible, to interpret accurately film exposed to combinations of X-ray or gamma radiation of various energies. Such mixtures of high and low energy photons are characteristic of plutonium and transplutonium isotopes.Lithium fluoride, essentially equivalent in atomic number to human tissue, is particularly advantageous for personnel monitoring in plutonium processing areas because its response is relatively independent of photon energy.Other advantages of LiF dosimeters are stability, * The information contained in this article was developed during the course of work under Contract AT(O7-2)-1 with theU.S. AtomicEnergy Commission. wide dose range, low cost, accuracy, and small size.LiF dosimeters were attached to the film badges of sixty-six employees assigned to a plutonium finishing area at the Savannah River Plant in order to evaluate the operating performance and accuracy of LiF under field conditions. Workers in plutonium finishing areas are not normally exposed to significant quantities of beta radiation. Their skin exposure is determined routinely by comparing the density of the open-window portion of their film with the density of calibration film exposed to 238Pu X-rays and then adding the exposure indicated by the density behind the silver shield whi...

We report on the use of the Surface PhotoVoltage (SPV) technique to monitor the Si surface bonding arrangement, and the impurity metallic contamination level prior to critical diffusion processes via the indirect measurement of surface charge and diffusion length, respectively. We show that the effectiveness of the pre-diffusion wet chemical cleaning and rinsing sequences can be accurately monitored via the real-time, nondestructive SPV measurement. In particular the nature of the surface passivation/chemical oxide formed during the cleaning and rinsing operations can be monitored by quantitative surface charge measurements. The importance of the prior wafer history is highlighted, as is the role of the Si starting material and measurement parameters.

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