We propose a new technique to measure the infrared scintillation light yield
of rare earth (RE) doped crystals by comparing it to near UV-visible
scintillation of a calibrated Pr:(Lu$_{0.75}$Y$_{0.25}$)$_{3}$Al$_5$O$_{12}$
sample. As an example, we apply this technique to provide the light yield in
visible and infrared range up to \SI{1700}{nm} of this crystal.Comment: submitted to NIM 

Borghesani, A. F.

Braggio, C.

Brylew, K.

Carugno, G.

Chiossi, F.

Drozdowski, W.

Guarise, M.

English

arXiv

Chiossi, Federico

Borghesani, Armando-Francesco

Braggio, Caterina

Carugno, Giovanni

Guarise, Marco

Padua Research Archive

A new technique for infrared scintillation measurements

We propose a new technique to measure the infrared scintillation light yield of rare earth doped crystals by comparing it to near UV–visible scintillation of a calibrated Pr:(Lu0.75Y0.25)3Al5O12 sample. As an example, we apply this technique to provide the light yield in visible and infrared range up to 1700 nm of this crystal

CHIOSSI, FEDERICO

BORGHESANI, ARMANDO-FRANCESCO

BRAGGIO, CATERINA

CARUGNO, GIOVANNI

GUARISE, MARCO

Archivio istituzionale della ricerca - Università di Padova

Original Citation:A new technique for infrared scintillation measurementsElsevier B.V.Publisher:Published version:DOI:Terms of use:Open Access(Article begins on next page)This article is made available under terms and conditions applicable to Open Access Guidelines, as described athttp://www.unipd.it/download/file/fid/55401 (Italian only)Availability:This version is available at: 11577/3228016 since: 2017-05-12T15:43:20Z10.1016/j.nima.2017.01.063Università degli Studi di PadovaPadua Research Archive - Institutional RepositoryarXiv:1612.05507v1  [physics.ins-det]  16 Dec 2016A new technique for infrared scintillation measurementsF. Chiossia, K. Brylewb, A. F. Borghesanic, C. Braggioa, G. Carugnoa, W. Drozdowskib, M. GuariseaaDip. di Fisica e Astronomia and INFN, University of Padua, Via F. Marzolo 8, I-35131 Padova, ItalybInstitute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Grudziadzka 5, 87-100 Torun, PolandcCNISM unit and Dip. di Fisica e Astronomia, University of Padua, Via F. Marzolo 8, I-35131 Padova, ItalyAbstractWe propose a new technique to measure the infrared scintillation light yield of rare earth (RE) doped crystals bycomparing it to near UV-visible scintillation of a calibrated Pr:(Lu0.75Y0.25)3Al5O12 sample. As an example, we applythis technique to provide the light yield in visible and infrared range up to 1700 nm of this crystal.Keywords: Infrared light yield, Pr:LuYAG, Radioluminescence1. IntroductionA new concept, all-optical particle radiation detector has been very recently proposed based on the mechanism ofupconversion in RE-doped materials [1]. This process, in which low energy incident optical radiation (infrared light- IR) is converted into higher energy emitted photons (visible light), is efficiently accomplished by incorporating REions in inorganic matrices due to their f -electrons configurations. In fact, ground state absorption (level 0) allowsthe rare earth ions to reach a metastable intermediate state (level 1), characterized by relatively long lifetimes (≈ms),then another photon delivered by a pump laser tuned to the transition 1 → 2 promotes the ion to a more energeticstate (level 2). Radiative transition from this latter excited state back to the ground state is then observed by meansof traditional detectors as photomultipliers (PMT) or photodiodes (PD). To date, this mechanism has been extensivelyapplied for the development of lasers and optical devices [2, 3] but its applicability in the field of particle detectionhas not been deeply investigated.The visible light yield (LY) of this novel device depends on the upconversion efficiency and on the number ofRE-ions excited into the metastable level 1 per energy unit of the particle. This latter quantity can be estimated bystudying the LY in the IR band which very few articles in literature are concerned with [4]. Actually, there is littleinterest in the RE-doped crystals infrared scintillation for their long decay lifetimes and for the low quantum efficiencyof PMT in this spectral region.The aim of this work is to propose a method that allows us to tackle a systematic investigation of the IR LYin several different materials, composed of different matrices, dopants and concentrations. This method is based onthe luminescence comparison with a reference Pr:(Lu0.75Y0.25)3Al5O12 single crystal whose light yield in the nearUV-visible is known. Moreover, this method is applied to this crystal, thereby yielding its IR LY.2. Experimental setupThe mixed lutetium-yttrium aluminum garnet sample has been grown via Czochralsky method at ITME, Warsawand its preparation is described elsewhere [5]. The interest in mixed Pr:LuYAG crystals is related to its much betterperformance in terms of light yield and energy resolution as compared to either Pr:LuAG or Pr:YAG. The 5 × 5 × 5mm3 sample chosen for the present measurements has a reported light yield of 27 000 ph/MeV and a 5.3 % energyresolution in the UV-VIS range [5].To investigate its light yield in the IR band, the Pr:LuYAG sample is excited by X-rays generated by an electrongun that can be operated both in continuous and in pulsed mode sweeping the electron beam at 100 Hz frequency [6].The several µA intense electron beam impinges on a ∼10µm-thick tantalum foil placed in front of the sample to makesure that the whole crystal is excited only by X-rays. The scintillation response of the crystal sample is measuredPreprint submitted to Nuclear Instruments and Methods in Physics Research Section A December 19, 2016using Si (mod. Hamamtsu S1337-1010BQ) and InGaAs (mod. Thorlabs DET20C) PDs. The small contribution tothe PD signal of the X-rays that are not absorbed in the crystal and reach the PD can be estimated and then subtractedby covering the PD with an thin aluminum foil.In order to verify that the radioluminescence is determined by the Pr3+ ions emission, the X-rays excitation spectraare compared with those obtained when the crystal is irradiated with a pulsed, frequency-quadrupled Nd:YAG laser(266 nm). In fact, whereas the host matrix is transparent at this wavelength, the Pr3+ ions are directly excited into4 f 5d levels, thus allowing us to simulate the energy transfer process from the electron-hole recombination to the REions after the X-ray excitation.3. Spectroscopic analysisWe have recorded spectra of the Pr:LuYAG emission due to X-ray and UV excitation (Fig. 1). The OceanOptics650 RedTide and OceanOptics NIRQuest512 spectrometers were used for the 200–850 nm and 900–1700 nm regions,respectively.In both spectra one can clearly see emissions related to the same Pr3+ energy levels. We observe a strong 4 f 5d →4 f 2 emission in the range from 300 to 450 nm and narrow lines in the visible/near-infrared region due to emissionfrom levels 3P0, 1D2, 1G4. The spectra below 850 nm are similar to those reported by previous authors in a Pr:LuAGcrystal [7]. The main near-infrared transitions that we identify are: 1D2 → 3F3,4, 1G4 → 3H4 (900–1100nm) and1D2 → 1G4 (1400–1600nm). The emission from 1G4 is expected to be partially non radiatively quenched, whereasthe lower lying levels are strongly quenched in LuYAG matrix. As a consequence no mid-infrared emission is expectedfrom these latter levels.4. MethodWe measure the total number of charge carriers generated per X-ray pulse in the photodiode ne = QdR0/Gτ withQd being the time integrated photodiode signal, R0 = 1 MΩ the impedance of oscilloscope, G = 0.25 mV/fC and τ ≈480µs which are the gain and the time constant of the active integrator, respectively. If the PD quantum efficiency ηis constant in the considered range, ne is also given by equationne = Ein · LY · η ·∆Ω4pi(1 − R) (1)where Ein is the energy deposited in the sample, R the crystal reflectivity, ∆Ω = A/d2 is the solid angle subtended bythe PD with area A located at a distance d from the crystal. Moreover, the measured charge per pulse Qbs is relatedthrough a proportionality constant k to the energy released by X-ray pulse in the crystal. In fact, as shown in the Fig. 2,the measured luminescence Qd linearly depends on Qbs.It is then possible to obtain a general expression for the measured light yield in a definite wavelength range:LY =QdQbs d2 4piR0kGτ1η (1 − R) A . (2)As in the point source approximation the following expression holds trueQd(x)Qbs =( QdQbs d2)1(x0 + x)2=a(x0 + x)2(3)the parameters a =QdQbs d2 and x0 can be obtained by a fit of data recorded at different relative distances x of thephotodiode from the scintillating crystal, as shown in Fig. 3.We observe that in this type of measurements it crucial to precisely know the efficiency of the X-ray generationprocess, related to the previously mentioned proportionality constant k. The latter can be estimated if the X-ray energyis fully released in the sample and provided the LY and the a parameter of a generic crystal in any wavelength rangeare known. As the sensitivity of the detector that has been used to measure the light yield of our LuYAG:Pr crystal2reported in [5] peaks in the UV range, it is reasonable to expect that the reported light yield is mainly determinedby 4 f 5d → 4 f 2 radiative transitions. In addition, due to fast integration time the slow components might have beenunderestimated.In order to select the photodiode signal component due to the UV scintillation, the previously described measure-ments are repeated at a fixed distance with optical longpass filters (Thorlabs, FGL and FEL filter sets) located in frontof the photodiodes. The use of filters allows us to estimate the light yield in narrower bandwidths and with a betteraccuracy by taking into account the wavelength dependence of the photodiode’s responsivity.As the energy of the X-rays can be assumed to be in the range of few tens of keV, the LY of our sample measuredin [5] at 662 keV has to be reduced by 10%, in agreement with previously published data [8, 9, 10]. We report in Table1 the results of the light yield measurements in several optical ranges.Table 1: Measured light yield of the LuYAG:Pr crystal for different optical ranges.Optical Band [nm] LY [ph/MeV]200–495 24300495–780 6700780–1000 10001000–1100 13001100–1200 5001200–1700 11005. ConclusionsWe have demonstrated a practical way to accurately estimate the infrared light yield of a RE-doped crystal bycomparison with the near UV-visible luminescence of a reference crystal. The presented method allows us to makeaccurate LY measurements since it is based on the point-source approximation, as verified by performing measure-ments at several distances from the source, and because it is possible to vary the energy released per pulse in thecrystal and to average over several measurements. Furthermore, the use of several optical longpass filters reduces theerror due to the wavelength dependence of the photodiode quantum efficiency.The method has been applied to a (Lu0.75Y0.25)3Al5O12 crystal whose emission in the UV range had been previ-ously measured. In spite of its high LY in the UV, its emission in the near infrared band is limited to a few thousands ofph/MeV, probably due to the 1G4 manifold quenching. Although the states of our interest 3HJ and 3FJ, characterizedby ms-long radiative lifetimes, are efficiently populated by the relaxation of the higher manifolds, no mid-infraredemission is expected from them in this host matrix.The data reported in this work can be used to extend the LY measurements up to the mid-infrared band, providedthat photodiodes with a lower band gap than InGaAs are used.In order to identify the most suitable crystals for the development of the upconversion-based detector, severalRE-doped crystals are currently being investigated with the method described in this work. The preliminary resultsobtained for Nd:YAG and Tm:YAG are particularly encouraging for our aims and will soon be published.6. AcknowledgmentsThe growth of the crystals used in this research has been financed from the funds of the Polish National ScienceCentre granted on the basis of Decision no. DEC-2012/05/B/ST5/00324.The authors FC, AFB, CB, GC, and MG acknowledge the technical assistance of Mr. E. Berto and Mr. L.Barcellan.3References[1] A. F. Borghesani, C. Braggio, G. Carugno, F. Chiossi, A. Di Lieto, M. Guarise, G. Ruoso, M. Tonelli, Appl. Phys. Lett. 107 (2015) 193501.[2] R. Scheps, Progress in Quantum Electronics 20 (1996) 271.[3] J. C. Goldschmidt, S. Fischer, Advanced Optical Materials 3 (2015) 510.[4] W. W. Moses, M. J. Weber, S. E. Derenzo, D. Perry, P. Berdahl, L. A. Boatner, , IEEE Trans. Nucl. Sci. 45 (1998) 462.[5] W. Drozdowski, K. Brylew, A. J. Wojtowicz, J. Kisielewski, M. ´Swirkowicz, T. Łukasiewicz, J. T. de Haas, P. Dorenbos, Opt Mater 4 (2014)1207.[6] L. Barcellan, E. Berto, G. Carugno, G. Galet, G. Galeazzi, A. F. Borghesani, Review of Scientific Instruments 82 (2011) 095103.[7] W. Drozdowski, P. Dorenbos, R. Drozdowska, A. Bos, N. Poolton, M. Tonelli, M. Alshourbagy, IEEE Trans. Nucl. Sci. 56 (2009) 320.[8] W. Drozdowski, P. Dorenbos, J. T. de Haas, R. Drozdowska, A. Owens, K. Kamada, K. Tsutsumi, Y. Usuki, T. Yanagida, A. Yoshikawa,IEEE Trans. Nucl. Sci. 55 (2008) 2420.[9] L. Swiderski, M. Moszynski, A. Nassalski, A. Syntfeld-Kazuch, T. Szczesniak, K. Kamada, K. Tsutsumi, Y. Usuki, T. Yanagida,A. Yoshikawa, IEEE Trans. Nucl. Sci. 56 (2009) 934.[10] W. Chewpraditkul, K. Sreebunpeng, M. Nikl, J. A. Mares, K. Nejezchleb, A. Phunpueok, C. Wanarak, Radiat. Meas. 47 (2012) 1.0369 200  400  600  800  1000  1200  1400  1600Intensity [a.u.]Wavelength [nm]Laser Excitation4th orderFigure 1: Uncorrected emission spectra of Pr:LuYAG under 266 nm laser excitation (top) and X-ray excitation (bot-tom).4050100150200 0  10  20  30Q d [pC]Qbs [nC]No-filtersFGL495FGL780010203040 0  10  20  30Q d [pC]Qbs [nC]No-filtersFEL0800FEL1000FEL1100FEL1200Figure 2: Linear dependence of the visible and infrared integrated luminescence signal on the charge collected at theFarday cup. Different sets of longpass filters have been used to obtain the Si PD (left) data and the InGaAs (right)data. The filter name contains the cut in wavelength in nm.3.54.04.55.05.5 0  5  10  15  20  25Q d / Qbsx [mm]x10-30.20.50.81.01.2 0  5  10  15  20Q d / Qbsx [mm]x10-3Figure 3: Measurement of the a parameter with the Silicon (left) and the InGaAs (right) PD. The error bars are of thesame size as the symbols. The validity of the point source approximation is confirmed by the goodness of the fit.5

F. Chiossi

K. Brylew

A.F. Borghesani

C. Braggio

G. Carugno

W. Drozdowski

M. Guarise

Crossref

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

https://www.research.unipd.it/bitstream/11577/3228016/1/1612.05507.pdf

A new technique for infrared scintillation measurements

Abstract

Similar works

Full text

Available Versions

Padua Research Archive

Archivio istituzionale della ricerca - Università di Padova

Crossref