X-rays Physics

In regard to thermoluminescence (TL) applied to dosimetry, in recent times a number of researchers have explored the role of optical fibers for radiation detection and measurement.  Many of the studies have focused on the specific dopant concentration, the type of dopant and the fiber core diameter, all key dependencies in producing significant increase in the sensitivity of such fibers. At doses of less than 1 Gy none of these investigations have addressed the relationship between dose response and TL glow peak behaviour of erbium (Er)-doped silica cylindrical fibers (CF). For x-rays obtained at accelerating potentials from 70- to 130 kVp, delivering doses of between 0.1- 0.7 Gy, present study explores the issue of dose response, special attention being paid to determination of the kinetic parameters and dosimetric peak properties of Er-doped CF. The effect of dose response on the kinetic parameters of the glow peak has been compared against other fiber types, revealing previously misunderstood connections between kinetic parameters and radiation dose. Within the investigated dose range there was an absence of supralinearity of response of the Er-doped silica CF, instead sub-linear response being observed. Detailed examination of glow peak response and kinetic parameters has thus been shown to shed new light of the rarely acknowledged issue of the limitation of TL kinetic model and sub-linear dose response of Er-doped silica CF.

We have tested an X-ray diode working in reflection geometry, which uses commercial spark-plugs as plasma cathode. The results of the characterisation work confirm that the spark-plug plasma cathode is a reliable and long-lifetime electron source for X-ray diodes. After more than 10^6 shots, the X-ray dose, uniformity, and ionisation rate values guarantee an effective preionisation of excimer laser discharges. Owing to both the long lifetime and the substantial absence of maintenance, this X-ray diode seems suitable to preionise commercial gas lasers, such as excimer and TEA CO2 lasers.