Carlo Sanipoli

Spectrally resolved thermoluminescence of Cu and Eu doped Li2B4O7

Abstract Thermoluminescence studies are carried out on samples in powder form of Li2B4O7 doped with Cu or Eu impurities. Results concerning Li2B4O7:Cu are found in agreement with data in the literature and show that the emitting defects are of intrinsic nature. In Li2B4O7:Eu a further emission is attributed to extrinsic aggregate centres.

Defects in γ-irradiated KMgF3:Tl+ crystals

Abstract Optical and thermoluminescence studies on single crystals of the perovskite-like KMgF 3 , doped with T1 + ions, show that under β or γ irradiation various kinds of complex centers are formed. New absorption and luminescence bands are identified and measured as a function of temperature. The glow curve of the phosphor exhibits only one peak, and its features are in general promising for radiation dosimetry.

Complex centers in γ-irradiated LiF: Cu2+ crystals

Abstract Optical spectra of γ-irradiated LiF: Cu 2+ crystals are measured as a function of impurity concentration and coloration intensity. New defects are revealed by means of their luminescences and tentatively identified as aggregate color centers associated with the dopant ions. F 2 centers coupled to Cu 2+ ions show absorption at 375 nm and emission at 500 nm, while F 3 + centers coupled to Cu 2+ ions exhibit absorption at 470 nm and luminescence at 570 nm.

Pb2+ Defects in perovskite-like KMgF3 crystals

Abstract The physical properties of Pb2+ impurities in the perovskite-like lattice of KMgF3 are very similar to those of (ns)2 ions in alkali halides. The impurity inhomogeneous distribution leads to high dopant levels in the bottom region of the crystals, with a segregation coefficient equal to 0. 020. The optical features of the 336 nm emission support its attribution to luminescence of Pb2+ ions from the relaxed excited B state.

The RbBr:Cu+ fluorescence revisited

Abstract The fluorescence of Cu+ in RbBr was investigated in the temperature range 21–300 K, in particular by performing accurate lifetime and quantum yield measurements. By growing high purity samples it has been solved a 25 years old puzzle concerning a complex behaviour of the decay process, and the Cu+ de-excitation mechanism has been simply interpreted in terms of the traditional Pedrini model. Nevertheless, a squeezing effect for copper at low temperature was observed, which implies two temperature regions (above and below 40 K) for the decay parameters. This occurrence is explained on the basis of the Bosi and Nimis model, where not only an off-centre configuration but also a very low value for the Cu+ radius when compared to the Rb+ one in RbBr has been foreseen.

Modifications induced by ionizing radiations in the luminescence from single crystals of LiF:Mg,Cu,P

Abstract Single crystals of LiF:Mg,Cu,P have been grown and characterized with thermoluminescence and optical experiments. Good dosimetric features, such as linear response to radiation dose and resistance to thermal treatment, have been identified in spite of a poor sensitivity of the material. Absorption and emission bands have been assigned to color centers, impurity ions and complex defects.

On the RbBr:Cu+ fluorescence

The fluorescence of Cu☎ in RbBr was investigated in the temperature range 20–300 K, by recording both emission and excitation spectra and by performing accurate lifetime and quantum yield measurements. The de-excitation mechanism has been interpreted in terms of the traditional Pedrini model. Nevertheless, a change of the compression conditions for Cu☎ at low temperature was observed, which implies two temperature regions (above and below 40 K) for the decay parameters. This occurrence is related not only to off-centre configuration but also to a very low value for the Cu☎ radius when compared to the Rb☎ one in RbBr.

Thermoluminescence of pure and Eu-doped NaZnF3

Abstract Thermoluminescence of pure and Eu-doped NaZnF3 fluoroperovskite is studied in order to determine nature of emitting centres and possible dosimetric properties. Intrinsic and extrinsic defects, some of them due to surface oxidation processes, are related to peaks in the glow curves of the two systems.

Thermoluminescence Dating of Archaeological Ancient Roman Potteries

A large area on the northern slope of the Palatino is under excavation since autumn 1985 within the boundaries ofSacra Via to the North,Nova Via to the South,Atrium Vestae to the West and the Arch of Titus to che East; the sequence of human occupation in this residencial area, from medieval times down to the earliest phases of roman history, has been reconstructed. The main results obtained during excavations consist in the discovery of remains of large houses, facing theSacra Via and dating back to the 2nd half of the 6th century B.C. (599-550 B.C.). This paper reports the first collaboration work between the Physics Department of Rome University «La Sapienza» and the Archaeological Studies Department of Pisa University. For setting up the dating thermoluminescent system of the Physics Department, several samples from excavation have been studied by the quartz inclusion technique. The average TL age of the site gives a value of 603 B.C. with an error of ± 250 years. Since the archaeological age is in the range 630-580 B.C., the TL data are in good agreement with the historical values.RiassuntoQuesto lavoro riferisce sui primi risultati della collaborazione tra il Dipartimento di Fisica dell’Università di Roma «La Sapienza» ed il Dipartimento di Studi Archeologici dell’Università di Pisa ed in esso vengono confrontati i risultati ottenuti con metodi archeologici con quelli provenienti dalla datazione con il metodo della termoluminescenza di vari campioni provenienti dagli scavi. Per questa ricerca è stata usata la tecnica della inclusione di quarzo ed il risultato dà una stima dell’età dei campioni del 603 a.C. con un errore di ± 250 anni in buon accordo con la stima ottenuta con metodi archeologici che dà una età compresa tra il 630 ed il 580 a.C.