Gamma-ray Interaction Research Articles

Laser powder bed fusion of a pure tungsten ultra-fine single pinhole collimator for use in gamma ray detector characterisation

Laser Powder Bed Fusion is a leading additive manufacturing technology, whose use has been recently extended to refractory metals such as tungsten. This work was carried out to manufacture a pure tungsten pinhole collimator that would otherwise be difficult to produce using conventional methods such as machining. The laser powder bed fusion process was used to produce an ultra-fine 0.5 mm diameter hole running along a 40 mm long beam stop component. A laser powder bed fusion scanning strategy (laser energy density of 348 J/mm3) was selected with the aim of fabricating a high density tungsten component. The manufactured collimator was then used for gamma-ray detector characterisation. A collimated gamma-ray using a 241Am source mounted on an automated scanning table was used to study the gamma-ray interaction with respect to position in a semiconductor detector, so that the position-dependent charge collection process could be characterized. The 0.5 mm diameter fine tungsten collimator yielded a relatively narrower beam spot, leading to more accurate scan results. However that was at the expense of number of gamma rays detected per second. Overall, the 0.5 mm collimator allowed for higher resolution scans giving better detector characterisation results in comparison to a 1 mm diameter collimator.

Investigation of photon interaction parameters of polymeric materials using Monte Carlo simulation

Gamma-ray interaction parameters of polymers, that are generally preferred due to their light weight and high durability, have been investigated for their usefulness as dosimetric and shielding materials in medical, industrial and scientific fields of nuclear radiations. The simulations to estimate the attenuation by polymeric materials have been performed with FLUKA Monte Carlo code due to its reasonable flexibility and reliability. Radiation interaction related parameters such as mass attenuation coefficient (µm), relaxation length (ƛ), tenth-value layer (TVL), half-value layer (HVL), electronic cross-section (σt,el), atomic cross-section (σt,a), effective atomic number (Zeff) and effective electron density (Nel) have been reported for some useful polymeric materials like Polytetrafluoroethylene (C2F4)n, Bakelite (C9H9O)n, Polyethylene terephtalate (C10H8O4)n, Polypropylene (C3H6)n, Polysulfone (C27H22O4S)n, Polystyrene (C8H8)n, Polyethylene (C2H4)n, Natural Rubber (C5H8)n, Polymethyl methacrylate (C5H8O2)n and Polyvinylchloride (C2H3Cl)n. The investigations have been reported for the commonly used gamma sources with energies 59.5 (241Am), 80.9 (133Ba), 140.5 (99mTc), 356.5 (133Ba), 661.6 (137Cs), 834.8 (54Mn), 1173.2 (60Co) and 1332.5 (60Co) keV using the FLUKA simulation program. The results obtained by FLUKA Monte Carlo code agree well, having a relative deviation of less than 1%, with XCOM standard reference database. It was concluded from the study that FLUKA can be an alternative way to estimate various interaction parameters of polymeric materials especially when it is hard to set up an experiment. Also, among the chosen polymers Polyvinylchloride and Polytetrafluoroethylene are the best shielding polymers at lower and higher energy end in the range of 59.5 keV - 1332.5 keV respectively.

Optical, magnetic characterization, and gamma-ray interactions for borate glasses using XCOM program

In the present study, the optical characterization of borate glasses with composition 35Li2O − 10ZnO − 55B2O3 − xMnO2: x = 0, 0.5, 1.0, 1.5, and 2.0 wt% has been investigated. The absorption spectra measurements within the wavelength domain 200–1000 nm have been carried out. The optical energy gap of the investigated samples using the absorption spectrum fitting (ASF) model has been calculated. The molar refraction, molar polarizability, reflection loss, optical transmission for the samples were estimated. The metallization criterion, dielectric constant, refractive index, and energy band metallization criterion for the studied glasses were estimated. Magnetic property measurements for all glass samples were carried out at 300 K. Additionally, the prospects of gamma-ray interactions with the investigated glasses have been achieved through studying the total mass attenuation, coherent, Compton, photoelectric, and pair production interactions at photon energy in the range of 0.356–1.330 MeV. Results reveal that the optical and magnetic properties of the investigated glasses change with changing the MnO2 concentration. Studied glasses can be used as a candidate for optical fiber and optical devices application. In the other hand, at lower gamma photon energy range, the photoelectric absorption dominates with the glasses, while as the energy increases, the probability of Compton scattering and pair production become the most dominate interactions.

Effect of addition of cerium (III) nitrate hexahydrate on gamma ray interaction properties in acetone at various gamma energies obtained by Compton scattering technique

The objective of the present work is to assign radiation interaction parameters to the solutions of cerium (III) nitrate hexahydrate [(Ce(NO3)3.6H2O)] in different concentrations dissolved in acetone [(CH3)2CO]. The photons scattered from cylindrical aluminum target result in secondary photon beam of desired energy and were detected using 2″ × 2″ NaI(Tl) scintillation spectrometer. The results show a decrease in mass attenuation coefficient (μm), effective atomic number (Zeff) and Electron density (Nel) with the increasing gamma photon energies and decreasing concentrations. The values of Computed tomography (CT) number, interpreters of CT scan, are found to be increasing linearly with increase in concentration and exponentially with increase in Zeff. These results show a good agreement with the theoretical values obtained from WinXCom.

Dual-ended readout of bismuth germanate to improve timing resolution in time-of-flight PET

The scintillator bismuth germanate (BGO) has attractive properties for positron emission tomography (PET) systems such as high stopping power, high photo-fraction, and relatively low cost. However, its moderate scintillation light yield and slow rise and decay time compared to lutetium (yttrium) oxyorthosilicate (L(Y)SO) results in a degradation of coincidence timing resolution when scintillation photons are used for timing. Recently, it has been reported that the coincidence timing resolution of BGO can be improved by detecting Cerenkov photons, while scintillation photons still provide energy information. However, the measured coincidence timing spectrum showed much longer tails compared to the single Gaussian distribution. Because of this, TOF PET detectors based on BGO will perform worse than the full width at half maximum (FWHM) of the distribution, which is the most common metric for timing resolution, would suggest. From simulation studies, during the first few picoseconds, BGO generates ~16 Cerenkov photons per photoelectric interaction, following a 511 keV gamma ray interaction, while the probability of producing a scintillation photon during the first few picoseconds is very small. Therefore, when we configure a BGO crystal with dual-ended readout, the first arriving photons among the two opposing SiPMs are most likely Cerenkov photons, and by selecting the appropriate SiPM, an improvement in coincidence timing resolution can be achieved. In this study, both ends of a 3 × 3 × 20 mm3 BGO crystal were coupled to NUV-HD SiPMs. Trigger time differences from the dual-ended readout of BGO were widely distributed due to detecting a mixture of prompt Cerenkov and scintillation photons on both SiPMs. When using trigger times from only a single SiPM, the estimated coincidence timing resolution between two identical BGO detectors was 463 ps FWHM and 1463 ps FWTM. In contrast, when using trigger times from both SiPMs, the estimated coincidence timing resolution was 399 ps FWHM and 936 ps FWTM with no loss of events. Based on a recent report, high-bandwidth amplifiers were implemented and shown to further improve the estimated coincidence timing resolution to 331 ps FWHM and 923 ps FWTM. In summary, the coincidence timing resolution of BGO, most notably the FWTM, was significantly improved using time information from the dual-ended readout.

Black hole as a model of computation

Abstract This paper focuses on an alternative, more physically realistic model of computation than Etesi and Nemeti’s relativistic computer in a Malament-Hogarth spacetime (2002) that uses the black hole itself combined with an external observer equipped with a source and some method of measurement of gamma-rays, as opposed to sending a classical computer into a black hole and exploiting the properties of the spacetime to achieve hypercomputation. The source of output, Hawking radiation, is considered along with the constraints imposed by the holographic principle which limit the number of degrees of freedom in the system and consequently the maximum usable information. The Bekenstein-Hawking entropy is converted from the traditional form in terms of the horizon area to that of the Shannon entropy, establishing an analogy between the physical and computational perspectives of the system. Next examples are considered to establish the approximate order of the necessary excitation energy and the resulting gamma-ray interactions which form the input from the observer. Finally, the Turing completeness of the language for this model is considered through a simulation of the Turing machine. The goal is to introduce a model of computation that can later be used to study the relationship between computability and physical systems.

A feasibility study on 3D interaction position estimation using deep neural network in Cherenkov-based detector: a Monte Carlo simulation study

Cherenkov-based radiation detectors have been developed for time-of-flight positron emission tomography. As Cherenkov photons are emitted in an extremely short time, their use can improve time resolution. However, only up to 10 Cherenkov photons are yielded when a 511 keV gamma ray interacts with Cherenkov radiators, such as lead tungstate and lead fluoride (PbF2). Therefore, accurate estimation of the interaction position was difficult, and intense effort has been devoted to its improvement. We propose an estimation method for the 3D interaction position using a deep neural network. The network was evaluated by Monte Carlo simulations. For the simulations, a Cherenkov-based detector with a monolithic PbF2 radiator of 40 × 40 × 10 mm3 and a photodetector array were used. The gamma-ray interaction position in the radiator was estimated in 3D space by the neural network, whose inputs were the detection positions on the photodetector plane (xy plane) and timestamps of each photon from the detector. Training and validation datasets were generated while varying the single photon time resolution (SPTR) and readout pitch of the photodetector. By comparing several neural network architectures, we determined the best configuration to be the multilayer perceptron with 3 layers and 256 units. The full widths at half maximum of the xy plane and z axis (i.e., depth of interaction) were 1.54 and 1.59 mm with SPTR σ = 10 ps, respectively, and their cumulative histograms at half maximum were 0.65 and 0.81 mm also with σ = 10 ps, respectively. The proposed method retrieved higher estimation accuracy of the interaction position than an existing method based on the center of gravity and principal component analysis. Therefore, it is feasible to estimate the 3D interaction position in the Cherenkov-based detectors using deep neural networks.

Gamma photon protection properties of some cancer drugs for medical applications

Abstract Chemotherapy stops or slows down the growth and proliferation of cancer cells. Chemotherapy usually uses in combination with, surgery, radiotherapy or other treatments. Therefore, it is useful to calculate the photon interaction parameters to determine the energy accumulation and penetration in tissue due to the interaction of cancer drugs with radiation. In this work, the mass attenuation coefficient (μ/ρ), half value layer (HVL) and effective atomic number (Zeff) of some cancer drugs (Tadocel, Fluro-5, Erbitux, Carboplatin, Temodal, Tamoxifen, Endoksan and Oxaliplatin) have determined experimentally at 13.81, 17.7, 26.34 and 59.54 keV photons emitted from Am-241-point source by using Si(Li) detector. Besides, we calculated theoretically the gamma-ray interaction parameters using the WinXCOM software program. Next to these, utilizing the GP fitting approach, exposure buildup factors (EBF) of the drugs determined up to 40 mfp in the energy range 0.015–15 MeV. Experimental and theoretical results have been found to be in harmony. Oxaliplatin and Carboplatin have larger μ and Z eff and lower HVL values than the other drugs under study. The smallest EBF values are observed for Endoksan, Oxaliplatin and Carboplatin for all of the penetration depths. Oxaliplatin, carboplatin and endoksan possess significantly good radiation absorbing effect.

The Light-Trap: A novel concept for a large SiPM-based pixel for Very High Energy gamma-ray astronomy and beyond

Among the main disadvantages of using silicon photomultipliers (SiPMs) in large experiments are their limited physical area (increasing the cost and the complexity of the readout of a camera) and their sensitivity to unwanted wavelengths. This explains why photomultiplier tubes (PMTs) are still selected for the largest cameras of present and future Very High Energy (VHE) gamma-ray telescopes. These telescopes require photosensors that are sensitive to the fast and dim optical/near-UV Cherenkov radiation emitted due to the interaction of gamma rays with the atmosphere. Here we introduce a low-cost pixel consisting of a SiPM attached to a PMMA disk doped with a wavelength-shifting material, which collects light over a much larger area than standard SiPMs, increases sensitivity to near-UV light and improves background rejection. We also show the measurements performed in the laboratory with a proof-of-concept Light-Trap pixel that is equipped with a 3 × 3 mm2 SiPM collecting light only in the 300–400 nm band, covering an area ∼20 times larger than that of the same SiPM itself. We also present results from simulations performed with Geant4 to evaluate its performance. In addition to VHE astronomy, this pixel could have other applications in fields where detection area and cost are critical.

The 2014 TeV γ-Ray Flare of Mrk 501 Seen with H.E.S.S.: Temporal and Spectral Constraints on Lorentz Invariance Violation

Abstract The blazar Mrk 501 (z = 0.034) was observed at very-high-energy (VHE, E ≳ 100 GeV) gamma-ray wavelengths during a bright flare on the night of 2014 June 23–24 (MJD 56832) with the H.E.S.S. phase-II array of Cherenkov telescopes. Data taken that night by H.E.S.S. at large zenith angle reveal an exceptional number of gamma-ray photons at multi-TeV energies, with rapid flux variability and an energy coverage extending significantly up to 20 TeV. This data set is used to constrain Lorentz invariance violation (LIV) using two independent channels: a temporal approach considers the possibility of an energy dependence in the arrival time of gamma-rays, whereas a spectral approach considers the possibility of modifications to the interaction of VHE gamma-rays with extragalactic background light (EBL) photons. The non-detection of energy-dependent time delays and the non-observation of deviations between the measured spectrum and that of a supposed power-law intrinsic spectrum with standard EBL attenuation are used independently to derive strong constraints on the energy scale of LIV (E QG) in the subluminal scenario for linear and quadratic perturbations in the dispersion relation of photons. For the case of linear perturbations, the 95% confidence level limits obtained are E QG,1 > 3.6 × 1017 GeV using the temporal approach and E QG,1 > 2.6 × 1019 GeV using the spectral approach. For the case of quadratic perturbations, the limits obtained are E QG,2 > 8.5 × 1010 GeV using the temporal approach and E QG,2 > 7.8 × 1011 GeV using the spectral approach.

THE EFFECT OF GAMMA IRRADIATION AND PHOSPHATIC FERTILIZATION ON GROWTH, YIELD AND CHEMICAL COMPOSITION OF CARAWAY PLANTS

Recently, radiation technology is widely used to induce changes in plant characteristics for developing new products. So, a field experiment was carried out on alluvial clay soil at the Experimental Farm, Faculty of Agriculture, Menoufia University, Shebin El-Kom, Egypt (30.52oN and 30.99oE) during the two successive growing winter seasons, i.e. 2012/2013 and 2013/2014 on caraway plants (Carum carvi L.) to evaluate both individual and combined effects of different doses of gamma rays (0, 20, 40 and 80 Gy) and different levels of phosphorus (P) fertilizer ( 0, 50, 75, 100 and 125% of the recommended dose which are 0, 100, 150, 200 and 250 kg ordinary super phosphate/fed, respectively, P2O5=15.5 % ) on growth and yield components. The layout of this experiment was a split-plot design with the main plots that arranged in a randomized complete blocks design with three replicates. The results revealed that irradiation by gamma rays individual and/or combined with (P) fertilizer caused significant increases in vegetative growth characters, i.e. plant height (cm), number of main branches/plant and fresh weight of whole plant (g) along with yield and oil yield parameters, i.e. number of umbels/plant, dry weight of umbels/plant (g), fruit yield (g/plant and kg/fed), volatile oil % and oil yield (cc/plant and l/fed) as well as chemical composition, i.e.photosynthetic pigments, N, P, K, crude protein and total carbohydrate contents (%) in plants. The maximum increase in the most cases of (vegetative growth characters, yield parameters and oil production) was noticed by using gamma rays at (40 Gy) combined with (P) fertilizer at (200 kg/fed).There was a gradual increase in total carbohydrate content (%) as a result of using different levels of (P) fertilizer and reached its maxima by using the interaction of gamma rays at (40 Gy) combined with (P) fertilizer at (250 kg/fed). Finally, the interaction treatments of gamma rays at the low dose (20 Gy) + each of (P) fertilization at rates of (150 or 200 kg/fed) produced the maximum content of chlorophyll a in the first and second seasons, respectively. Moreover, it could be mentioned that the highest value of chlorophyll b was happened by exposing seeds tothe moderate dose of gamma rays (40 Gy) and combined by each of (P) fertilization at (150 or 200 kg/fed) through the first and second seasons, respectively.

Application of Monte Carlo Method for Gamma ray Attenuation Properties of Lead Zinc Borate Glasses

This work aims to introduce an useful computational model, based in Monte Carlo simulation, which can be used in practical application, and this paper presents values determined using a Monte Carlo algorithm for linear attenuation coefficient of lead zinc borate glasses with different percentages of PbO. The simulation results have been verified with predictions from the XCOM program in the studied energy region from 1 keV to 2000 keV and experimental results. Thus, this verification indicated that this research method can be followed to determine the interaction and attenuation of gamma rays with the several energies in different materials. Also, the values of mean free path and the half-value layer were calculated using the values of the linear attenuation coefficient. The dependence of these radiation shielding parameters on the energy of impinging gamma ray and the ratio of substances changes has been examined.

Compton PET: a simulation study for a PET module with novel geometry and machine learning for position decoding

This paper describes a simulation study of a positron emission tomography (PET) detector module that can reconstruct the kinematics of Compton scattering within the scintillator. We used a layer structure, with which we could recover the positions and energies for the multiple interactions of a gamma ray in the different layers. Using the Compton scattering formalism, the sequence of interactions can be estimated. The true first interaction position extracted in the Compton scattering will help minimize the degradation of the reconstructed image resolution caused by intercrystal scatter events. Because of the layer structure, this module also has readily available user-defined resolution for the depth of interaction. The semi-monolithic crystals enable high light collection efficiency and an energy resolution of ∼10% has been achieved in the simulation. We used machine learning to decode the gamma ray interaction locations, achieving an average spatial resolution of 0.40 mm. Our proposed detector design provides a pathway to increase the sensitivity of a system without affecting other key performance features.

Gamma ray interactions with samarium doped strontium phosphate glasses

Collective optical, photoluminescence, FTIR spectral studies of increasing Sm2O3 ions (3.2–15 mol%) in strontium phosphate host glass were measured before and after irradiated with (8 Mrad dose) by gamma ray. The undpoed optical spectrum revealed a clear UV absorption peak at 230 nm due to trace iron impurity. Sm2O3-doped glasses exhibit extended visible near IR peaks in two rows, the first extended from 330 to 500 nm with small peaks and the second series extends from 900 to 2500 nm with distinguished peaks. This extended optical-near IR spectral absorption peaks belong to trivalent samarium ions. The photoluminescence (PL) spectra after excitation at 402 nm reveal four PL peaks with the decrease in intensity with increasing samarium content. Upon excitation at 596 nm, 11 peaks are identified and three of which are splitted into component peaks and their intensities decrease with increasing Sm2O3 content. FTIR spectra show distinguished vibrational peaks at the wavenumber range 2000–400 cm−1. Some of the bands are very prominent and obviously revealing some modifications of the phosphate network by the addition of increasing Sm2O3 content.

Radiation shielding parameters of BaO–Nb2O5–P2O5 glass system using MCNP5 code and XCOM software

The radiation shielding properties (mass attenuation coefficient, effective atomic number, half value layer, mean free path and exposure buildup factor) of xBaO–20Nb2O5–(80−x)P2O5, (x = 20, 30, 40, 50 and 60 mol%) glass system has been evaluated. The mass attenuation coefficient was calculated at 31, 59.5, 80, 356 and 662 keV photon energies using XCOM program and MCNP5 code. The obtained results are found to be in good agreement. The values of mass attenuation coefficient and effective atomic number of the present glass system are found to be increasing with increasing the BaO content at all energies. The mean free paths of the present samples are found to be smaller than the mean free path of some standard shielding glasses and concretes. This establishes that the present glasses possess better radiation shielding competence. The effect of the penetration depth on exposure buildup factor has also been discussed to through more light on their gamma ray interaction behaviour. The 60BaO–20Nb2O5–20P2O5 sample was found to be the best gamma shield.

Gamma rays interactions with Bi2O3-doped Na2O–CdO–P2O5 glasses assessed by collective optical and FT infrared absorption spectroscopy

Undoped and Bi2O3-doped glasses from the system Na2O–CdO–P2O5 were prepared and studied through investigating their optical and FTIR spectra before and after gamma irradiation beside measuring their thermal expansion properties. Optical spectra reveal distinct UV absorption with additional peaks upon introducing Bi2O3 added with different concentrations from 1 to 7.5%. The UV absorption of the undoped sample is related to trace iron impurities while the extended UV absorption peaks are correlated with absorption of Bi3+ ions. FTIR spectra show condensed phosphate groups (Q2, Q3 units) beside the sharing of bismuth ions in their vibrational sites. Gamma irradiation causes limited changes in the UV spectra but involves the generation of an induced visible band in the undoped glass. These changes are assumed to be due to some suggested photochemical reactions on the trace iron impurities and the formation of an induced visible (POHC) band on the phosphate network. Careful inspection of the selected deconvoluted spectra for the undoped glass and doped (7.5 wt%) supports the introduced assumptions. The thermal expansion parameters are correlated with the type of bonding of bismuth ions within the network structure.

Automated spectra analysis of in situ radioactivity measurements in the marine environment using NaI(Tl) detector

The NaI(Tl) detector has become the main way of research and application of in-situ radioactivity measurement in the marine environment due to many advantages on detection efficiency, power consumption, cost and applicability. But for the poor energy resolution and there is a high background in the low energy region of the spectrum measured mainly originating from the Compton scattering of natural radionuclides such as 40K with high concentrations in seawater, it is difficult and also an interesting topic for NaI(Tl) detector to identificate the radionuclides and calculate them in seawater by analyzing the spectra measured. In this paper, an in situ NaI(Tl) detector developed for the marine environment was energy, resolution and efficiency calibrated. The detection response matrix was calculated by taking all the responsible processes and interactions of gamma rays in water as well as in the detector into account using Monte Carlo simulation method. And then an improved Richardson-Lucy (R-L) deconvolution algorithm was proposed to reconstruct the gamma spectrum measured in the seawater to remove as efficiently as possible the background counts into the corresponding photopeaks. The original spectrum was transformed from poor energy resolution to the corresponding deconvolution spectrum of the high energy resolution with several isolated photopeaks. The experiments of synthetic spectrum and measured spectrum both showed promising results for the radionuclide qualitative and quantitative analysis.

Particle-in-cell simulations of pair discharges in a starved magnetosphere of a Kerr black hole

We investigate the dynamics and emission of a starved magnetospheric region (gap) formed in the vicinity of a Kerr black hole horizon, using a new, fully general relativistic particle-in-cell code that implements Monte Carlo methods to compute gamma-ray emission and pair production through the interaction of pairs and gamma rays with soft photons emitted by the accretion flow. It is found that when the Thomson length for collision with disk photons exceeds the gap width, screening of the gap occurs through low-amplitude, rapid plasma oscillations that produce self-sustained pair cascades, with quasi-stationary pair and gamma-ray spectra, and with a pair multiplicity that increases in proportion to the pair production opacity. The gamma-ray spectrum emitted from the gap peaks in the TeV band, with a total luminosity that constitutes a fraction of about 10−5 of the corresponding Blandford−Znajek power. This stage is preceded by a prompt discharge phase of duration ∼rg/c, during which the potential energy initially stored in the gap is released as a flare of curvature TeV photons. We speculate that the TeV emission observed in M87 may be produced by pair discharges in a spark gap.

Multilayer phoswich scintillators for neutron / gamma discrimination

MultiLayer Phoswich (MLP) scintillators have been studied for fission neutron detection by Monte-Carlo simulations and experimental tests. n/γ discrimination behavior of these systems and their angular dependencies have been characterized. The possibility to carry on a neutron counting system based of such an approach has been proven, and according to the results, an optimal thickness of layers for fission neutron counting was found around [100–150] μm. But, contrary to current liquid or solid-state discrimination scintillators, it appears that MLP-based neutron counting systems cannot directly classify neutron and gamma-ray interaction events from pulse shape analysis. To operate properly, it is therefore required to implement a compensation algorithm in the system readout.

Gamma Rays Interactions with Transition Metal Doped-Soda lime Phosphate Glasses Evaluated by Collective Optical, FTIR Spectral Measurements

MnO2, NiO, CoO and CuO doped in soda lime phosphate host glass were prepared. Combined optical and FTIR spectra were measured for the studied glasses before and after gamma irradiation. Some optical and physical properties such as density, molar volume, optical band gap energy and the width of the band tails (Urbach energy) were measured or calculated for the glass samples before and after irradiation. Optical absorption spectra of the selected TM ions reveal specific absorption bands which are characteristics for each ion in accordance with its configuration, valence or coordination state exhibited by the TM ion in the host phosphate glass. Gamma irradiation causes obvious changes which vary with the type of transition metal ion and in some cases obvious shielding effects are identified towards gamma irradiation. FTIR spectra show vibrational bands which are correlated with specific phosphate groups (mainly Q2 and Q3 units) which are related to the percent of constituting glass-forming component oxide. The measured optical properties confirmed the results of the optical absorption spectroscopy which indicate that copper-doped samples have some shielding behavior towards the irradiation process.