Four phosphors CaSO4: Eu; MgSO4: Eu; MgSO4: Eu, Mn and MgSO4: Eu, P have been prepared and their thermoluminescence (TL) spectra were obtained. For MgSO4: Eu a main glow peak due to Eu2+ ions is seen at～144◦C and 440 nm while for CaSO4: Eu this occurs at～144◦C and 390 nm. Further MgSO4: Eu glow peaks at～145◦C; ～190◦C, ～260◦C and ～360◦C for 590 and 620 nm wavelengths are identi9ed as Eu3+ ion emissions. These characteristic glow peaks occur at almost the same temperatures as in MgSO4: Dy. In MgSO4: Mn glow peaks at 140◦C and 190◦C for a broad wavelengthband about 660 nm are seen from the Mn ions. When MgSO4 is co-doped withEu and Mn the Eu2+ and Eu3+ ion glow peaks are remarkably suppressed while the 660 nm broad emission band glow peaks at～140◦C and 190◦C remain withh ighintensity contributed from the Mn luminescence centers. Emission spectra in MgSO4: Eu and the MgSO4: Eu,P show that the MgSO4: Eu3+ glow peak at 260◦C for 590 and 620 nm shifts to 280◦C, while the Eu2+ ion glow peak at～144◦C remains but withreduced intensity. Thus, the effect of the P co-dopant in MgSO4: Eu,P is exactly similar to its role in MgSO4: Dy; P, i.e. shifting the 260◦C peak to 280◦C with enhanced intensity and suppressing the intensity of the other peaks. The main glow peak at～144◦C and 440 nm from Eu2+ ions shows significant difference from the characteristic glow peaks of Eu3+ ions. It is found that the wavelength of the Eu2+ ion glow peak is inversely proportional to the radius of the cation of the host sulfate. By contrast the wavelengths of the Eu3+ ion glow peaks remain unchanged in di=erent sulfates.

The MgSO4: Dy, Mn thermoluminescence (TL) phosphors have been prepared by co-doping with various concentrations of activators the Dy and Mn. The dose-responses to gamma-rays are studied by deconvolution of the TL glow curves. It is found that the TL sensitivity of the MgSO4: Dy, Mn phosphor is comparable to that of the phosphor LiF: Mg, Ti. Besides, there is only one main dosimetric peak at 3838C in its TL glow curve. The trap parameters of the dosimetric peak were obtained as activation energy E～1.972 eV, the frequency-factor s～4.294×1014s-1 and the kinetic order b≈2 by fitting the glow curves with general-order kinetics. The area of this dosimetric peak is～90% of the integral area of the whole glow curve for a gamma dose range of 0.1 Gy-20 kGy. The dose response of MgSO4: Dy, Mn to gamma-rays in this dose range is supralinear. There are no radiation damage effects observed in TL glow curves above 1 kGy as that occurred in LiF dosimeters.

The MgSO4: Dy, P and MgSO4: Dy, P, Cu phosphors have been developed and studied by the thermoluminescence (TL) glow curves and dose responses to gamma radiation. The TL sensitivity of MgSO4: Dy, P phosphor is higher than that of LiF: Mg, Ti. One main dosimetric peak at about 283.6◦C and a satellite peak at about 352.7◦C are involved in the TL glow curve of the MgSO4: Dy, P which was measured with a heating rate of 5◦C s−1 and deconvoluted by the general order kinetics equation to obtain the peak parameters and trap parameters of the elementary TL peaks. The dose responses to gamma rays in the dose range from 0.1 Gy to 20 kGy were obtained and fitted by the composite action dose response function to get the nonlinear characteristic parameters, one-hit factor R and characteristic dose D0, which indicate that the TL dose responses for the two peaks of MgSO4: Dy, P are supralinear. When a trace amount of Cu was co-doped into MgSO4: Dy, P the TL glow peak at 352.7◦C was suppressed and the TL sensitivity and the nonlinearity of dose response for the main dosimetric peak at 283.6◦C critically depends on the concentration of doped Cu. The dose response of MgSO4: Dy, P, Cu (0.1 mol%, 0.5 mol%, 0.01 mol%) phosphor is linear–sublinear. The MgSO4: Dy, P, Cu (0.1 mol%, 0.5 mol%, 0.004 mol%) phosphor has a wider linear range in the dose response than MgSO4: Dy, P (0.1 mol%, 0.5 mol%) and its TL sensitivity is close to MgSO4: Dy, P (0.1 mol%, 0.5 mol%). It may be a candidate with which to measure radiation dose under higher dose circumstances.

The track structure model of heavy ion cross sections was developed by Katz and co-workers in the 1960s. In this model the action cross section is evaluated by mapping the dose-response of a detector to r rays (modeled from biological target theory) onto the radial dose distribution from δ rays about the path of the ion. This is taken to yield the radial distribution of probability for a "hit" (an interaction leading to an observable end-point). Radial integration of the probability yields the cross section. When different response from ions of different Z having the same stopping power is observed this model may be indicated. Since the 1960s there have been several developments in the computation of the radial dose distribution, in the measurement of these distributions, and in new radiobiological data against which to test the model. The earliest model, by Butts and Katz, made use of simplified δ ray distribution functions, of simplified electron range-energy relations, and neglected angular distributions. Nevertheless it made possible the calculation of cross sections for the inactivation of enzymes and viruses, and allowed extension to tracks in nuclear emulsions and other detectors and to biological cells. It set the pattern for models of observable effects in the matter through which the ion passed. Here we outline subsequent calculations of radial dose which make use of improved knowledge of the electron emission spectrum, the electron range-energy relation, the angular distribution, and some considerations of molecular excitation, of particular interest both close to the path of the ion and the outer limits of electron penetration. These are applied to the modeling of action cross sections for the inactivation of several strains of E-coli and B. subtilis spores where extensive measurements in the "thin-down" region have been made with heavy ion beams. Such calculations serve to test the radial dose calculations at the outer limit of electron penetration. We lack data from which to test these calculations in regions close to the path of the ion aside from our earliest work on latent tracks in plastics, though it appears that the criterion then suggested for the threshold of track formation, of a minimal dose at a minimal distance (of about 20 Å, in plastics), remains valid.

Phosphor emission spectra are presented for MgSO4 doped with Dy, MgSO4 co-doped with Dy and Mn, MgSO4 co-doped with Dy and P, and MgSO4 co-doped with Dy, P and Cu. All spectral wavelengths are related to transitions in Dy3+ ions. In a broad wavelength band around ～660 nm, three dimensional glow curves at ～140 and ～190◦C in the MgSO4:Mn spectrum are due to emissions from Mn2+ ions. For MgSO4 co-doped with Dy and Mn the main glow peak occurs at ～380◦C, about 20◦C above the fourth glow peak obtained in MgSO4 doped with Dy. The emission spectra of the MgSO4: Dy, Mn phosphor show the competitive de-excitation processes between Dy3+ and Mn2+ ions. This indicates that rare earth and Mn ions in MgSO4: Dy, Mn form complex defects that dominate the traps and recombinations. The MgSO4: Dy glow peak at around 260◦C shifts in MgSO4: Dy, P to ～280◦C with enhanced intensity, while the ～360◦C glow peak remains in place with a slightly increased intensity. The enhanced transluminescence (TL) sensitivity obtained by co-doping with P is probably due to charge compensation. The relative intensities vary between the 480 and 580 nm band of the glow peaks while the temperature (～280◦C) is unchanged for MgSO4 co-doped with Dy, P and Cu. The Cu+2 or Cu+1 ions act as charge compensators to the Dy3+ ions and reduce the concentration of Mg2+ vacancies in MgSO4: Dy, P, Cu. This results in changes to the dose response characteristics.