Adrie J.J. Bos | Delft University of Technology (original) (raw)

Papers by Adrie J.J. Bos

Thermally stimulated luminescence (TSL) is known as a technique used in radiation dosimetry and d... more Thermally stimulated luminescence (TSL) is known as a technique used in radiation dosimetry and dating. However, since the luminescence is very sensitive to the defects in a solid, it can also be used in material research. In this review, it is shown how TSL can be used as a research tool to investigate luminescent characteristics and underlying luminescent mechanisms. First, some basic characteristics and a theoretical background of the phenomenon are given. Next, methods and difficulties in extracting trapping parameters are addressed. Then, the instrumentation needed to measure the luminescence, both as a function of temperature and wavelength, is described. Finally, a series of very diverse examples is given to illustrate how TSL has been used in the determination of energy levels of defects, in the research of persistent luminescence phosphors, and in phenomena like band gap engineering, tunnelling, photosynthesis, and thermal quenching. It is concluded that in the field of luminescence spectroscopy, thermally stimulated luminescence has proven to be an experimental technique with unique properties to study defects in solids.

Journal of Luminescence, 2015

ABSTRACT The spectroscopic characterization down to 10 K was performed for undoped and Ln doped C... more ABSTRACT The spectroscopic characterization down to 10 K was performed for undoped and Ln doped CaLa4(SiO4)3O (Ln=Eu3+, Eu2+, Ce3+, Dy3+, Tb3+). Based on the experimental and literature data the scheme was constructed showing the vacuum referred binding energy (VRBE) of electrons in lanthanide states and band states in CaLa4(SiO4)3O. This scheme predicts that co-doping with Eu2+ and Ln3+ (Ln=Dy, Nd) will induce afterglow. Thermoluminescence and afterglow were indeed measured and compared with a commercial SrAl2O4:Eu, Dy afterglow phosphor.

Radiation Protection Dosimetry, 1999

Radiation Protection Dosimetry, 2004

A new type of mini multi-element tissue-equivalent proportional counter (TEPC) based on a gas ele... more A new type of mini multi-element tissue-equivalent proportional counter (TEPC) based on a gas electron multiplier (GEM) has been designed and constructed. This counter is in particular suitable to be constructed with a small sensitive volume so that it can be used for microdosimetry in intense pulsed radiation fields to measure the microdosimetric spectrum in the beam of, for instance, a clinical linear accelerator. The concept lends itself also for a mini multi-element version of the counter to be used for applications in which a high sensitivity is required. In this paper, we present the first microdosimetric measurements of this novel counter exposed to a 14 MeV monoenergetic neutron beam and a californium (252Cf) source for a counter cavity diameter of 1.8 mm simulating 1.0 microm tissue site size. The measured spectra showed an excellent agreement with spectra from the literature. The specific advantages of the TEPC-GEM are discussed.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003

Thermoluminescence (TL) emission spectra and TL glow curves of powder samples of YPO 4 :Ce 3+ , L... more Thermoluminescence (TL) emission spectra and TL glow curves of powder samples of YPO 4 :Ce 3+ , Ln 3+ (Ln 3+ = Nd 3+ , Sm 3+ , Dy 3+ , Ho 3+ , Er 3+ , Tm 3+) were measured in order to investigate the nature of the trapping centres and to locate the lanthanide energy levels relative to the valence and conduction bands of the YPO 4 host. Trap depths were determined by three different TL techniques (simple formula, various heating rate method and glow curve fitting) and compared with an earlier developed predictive energy level scheme. The nature of the trapping centres agrees with that predicted by the energy level scheme. Further, the trend of trap depths of the divalent lanthanides (Ln 2+ = Nd 2+ , Sm 2+ , Dy 2+ , Ho 2+ , Er 2+ , Tm 2+) agrees very well with the trend of levels determined by three different thermoluminescent techniques. It is concluded that the energy level scheme can help in the development of new TL materials suitable in dosimetry.

The optically stimulated luminescence (OSL) signal of natural quartz measured under constant stim... more The optically stimulated luminescence (OSL) signal of natural quartz measured under constant stimulation power (CW-OSL) is a featureless decay curve where underlying components cannot be identified easily. Visual interpretation of quartz OSL signals is easier if signals are shown in spectrum-like form. This can be achieved either through ramped stimulation, or by transforming a measured CW-OSL curve into a pseudo OSL curve. We show that both give similar results, but that transformation should be preferred as CW-OSL provides best signal-to-noise ratios. We present different transformation methods to obtain pseudo OSL curves and discuss the advantages and disadvantages of each method. In addition, we show that different pseudo OSL transformations can be used to emphasize specific aspects of the OSL signal. We conclude that transformation of CW-OSL to pseudo hyperbolically modulated OSL provides the most useful visualization of the quartz fast OSL component. Pseudo parabolic modulated OSL is the transformation of choice for showing the slow component(s). The pseudo OSL curves can be used for rapid visual inspection of the relative contribution of the OSL components prior to further analysis.

Radiation Protection Dosimetry, 2005

The characteristics of the radionuclides (170)Tm and (169)Yb are highly interesting for their use... more The characteristics of the radionuclides (170)Tm and (169)Yb are highly interesting for their use as high dose-rate brachytherapy sources. The introduction of brachytherapy equipment containing these sources will lead to smaller required thicknesses of the materials used in radiation protection barriers compared with the use of conventional sources such as (192)Ir and (137)Cs. The purpose of this study is to determine the required thicknesses of protection material for the design of the protecting walls. Using the Monte Carlo method, transmission data were derived for broad-beam geometries through lead and concrete barriers, from which the first half value layer and tenth value layer are obtained. In addition, the dose reduction in a simulated patient was studied to determine whether transmission in the patient is a relevant factor in radiation protection calculations.

The Journal of Physical Chemistry C, 2015

Phys. Chem. Chem. Phys., 2015

Low-temperature (10 K) photoluminescence excitation and emission spectra of undoped Sr3SiO5 as we... more Low-temperature (10 K) photoluminescence excitation and emission spectra of undoped Sr3SiO5 as well as Ce(3+) and Eu(3+) single doped Sr3SiO5 have been investigated. They show the host exciton band and the O(2-) to Eu(3+) charge transfer band at 5.98 eV (207 nm) and 3.87 eV (320 nm) respectively. Low-temperature thermoluminescence measurements are reported for Ce(3+) and lanthanide (Er, Nd, Sm, Dy, Er and Tm) co-doped Sr3AlxSi1-xO5. The results show that Ce(3+) is the recombination centre and Nd, Sm, Dy and Tm work as electron traps with trap depths of 0.95 eV, 1.89 eV, 1.02 eV, and 1.19 eV, respectively. Thermoluminescence excitation spectra of Sr2.98Al0.02Si0.98O5:0.01Ce(3+),0.01Dy(3+) show that the traps can be charged by 260 nm UV excitation.

Journal of Thermal Analysis and Calorimetry, 2015

Physical Review B Condensed Matter and Materials Physics, May 19, 2009

We present mathematical descriptions of optically stimulated luminescence (OSL) signals under lin... more We present mathematical descriptions of optically stimulated luminescence (OSL) signals under linearly, hyperbolically, exponentially, and reciprocally increasing stimulation intensity for a one-trap one-recombination-center model assuming charge transfer governed by first-order kinetics. Depending on the stimulation mode, the OSL signal can be monotonically increasing, monotonically decreasing, show a peak shape, or be constant. The shape of the OSL signal is controlled by a stimulation-rate parameter (governed by the stimulation mode) and a decay-rate parameter that is proportional to the photoionization cross section. We demonstrate that the luminescence signal as a function of time under exponentially increasing-optical stimulation (EM-OSL) shows the same evolution in time as the luminescence signal under hyperbolically increasing-thermal stimulation (HM-TL). This similarity allows a new interpretation of the Iṡt versus Int plot, where I is the optically stimulated luminescence intensity and t is the time. For a phosphor with several optically active traps, the OSL signal will contain several components. We show that the mathematical descriptions of the OSL signals under all stimulation modes can be related to the description of the OSL signal derived with continuous-wave (CW) stimulation. These so-called pseudo-OSL signals are helpful in a visualization of the various components in the OSL signal, where different pseudo-OSL transformations can be used to amplify different aspects. We demonstrate that the stimulation mode or pseudo-OSL transformation used has no effect on the overlap of the different OSL components. This implies that for the separation of multiple OSL components there is, in principle, no preference for a specific stimulation mode or pseudo-OSL transformation. Finally, we present a transformation related to hyperbolically modulated OSL which does facilitate separation of OSL components and may be of use for determining component specific photoionization cross sections or trapped-charge concentrations.

Radiation protection dosimetry, 2006

There is an increasing need for dosimetry of neutrons and charged particles. Increasing exposure ... more There is an increasing need for dosimetry of neutrons and charged particles. Increasing exposure levels are reported in the nuclear industry, deriving from more frequent in-service entries at commercial nuclear power plants, and from increased plant decommissioning and refurbishment activities. Another need stems from the compliance with requirements of the regulations and standards. The European Council directive 96/29 requires dosimetric precautions if the effective dose exceeds 1 mSv a(-1). On average, aircrew members exceed this value. Further, there is a trend of increasing use of charged particles in radiotherapy. The present situation is that we have reasonably good photon dosemeters, but neutron and charged particle dosemeters are still in need of improvements. This work highlights some of the developments in this field. It is mainly concentrated on some developments in passive dosimetry, in particular thermally and optically stimulated luminescent detectors, indicating the ...

Radiation protection dosimetry, 2004

Passive, solid-state detectors still dominate the field of neutron personal dosimetry, mainly tha... more Passive, solid-state detectors still dominate the field of neutron personal dosimetry, mainly thanks to their low cost, high reliability and elevated throughput. However, the recent appearance in the market of several electronic personal dosemeters for neutrons presents a challenge to the exclusive use of passive systems for primary or official dosimetry. This scenario drives research and development activities on passive dosemeters towards systems offering greater accuracy of response and lower detection limits. In addition, further applications and properties of the passive detectors, which are not met by the electronic devices, are also being explored. In particular, extensive investigations are in progress on the use of solid-state detectors for aviation and space dosimetry, where high-energy neutron fields are encountered. The present situation is also stimulating an acceleration in the development of international standards on performance and test requirements for passive dosi...