low-power photovoltaic cells batteries used as … · 3 low-power photovoltaic cells batteries used...

LOW-POWER PHOTOVOLTAIC CELLS BATTERIES

USED AS GAMMA RADIATION DOSE ESTIMATORS

V. FUGARU1, R.O. DUMITRESCU2,3, C.D. NEGUT1

1Horia Hulubei National Institute for Nuclear Physics and Engineering,

30 Reactorului, P.O.Box MG-6, RO-077125 Bucharest-Magurele, Romania 2Doctoral School of Physics – University of Bucharest,

P.O.B. MG-11, Romania 3CBRN Defence and Ecology Scientific Research Centre, 041309 Bucharest, Romania

Corresponding author: [email protected]

Received October 30, 2017

Abstract. In this paper, the possibility of using commercial low-power photovoltaic

cells batteries as sensors for the estimation of the gamma radiation dose in a certain point in

space and for certain energy in particle accelerators related experiments, when the occurred

nuclear reactions are involving the presence of higher or lower gamma radiation fields, was

studied. Initially, three low-power photovoltaic cells batteries were exposed to three

different well-known gamma radiation doses (33.45 kGy, 35.61 kGy and 37.9 kGy) and

one was kept as blank (0 kGy), and then, an analysis of some of their functional parameters

(short circuit current, open circuit voltage, external quantum efficiency) was performed.

The functional parameters were studied with respect to the illuminance conditions and to

the absorbed dose values in order to determine which of them can be used in gamma

radiation dosimetry. Five different artificial lighting conditions were used, and, in each

case, the values of sensitivity of the sensors (expressed in nA/Gy) and their external

quantum efficiencies were determined. As it was shown in this study, low-power

photovoltaic cells batteries can indeed be used as gamma radiation dose estimators, and

even more, can be used in complex gamma radiation fields distribution studies.

Key words: Low-power photovoltaic cells battery, illuminance, gamma radiation,

solid state dosimetry.

1. INTRODUCTION

Nuclear radiations are emissions of waves or particles, carrying energy.

These energies induce some changes to the structure of exposed materials

(in particular on electrical and optical properties) [1–10]. Using this “cause-effect”

relation, the estimation of an unknown gamma radiation dose induced to an

exposed material can be done.

Romanian Journal of Physics 63, 903 (2018)

Article no. 903 V. Fugaru, R.O. Dumitrescu, C.D. Negut 2

In this paper, the possibility of using commercial low-power photovoltaic

battery cells as sensors for the estimation of the gamma radiation dose in a certain

point in space and for certain energy in particle accelerators related experiments,

when the occurred nuclear reactions are involving the presence of higher or lower

gamma radiation fields, was studied.

A photovoltaic cells battery is a group of photovoltaic cells which provide

electrical power based on the conversion of light into electricity using

semiconducting materials that exhibit the photovoltaic effect. It is defined as a

device whose electrical characteristics, such as current, voltage, or resistance, vary

when exposed to light, and it is based on the following aspects: absorption of light

generating either electron-hole pairs or excitons, the separation of charge carriers

of opposite types and the separate extraction of those carriers to an external circuit

[11–17]. A photovoltaic cell consists of two or more layers of semiconductor

materials deposited on a surface made of a wide range of materials (FR4 type

0.5 mm glass textolite sheets in the case of the ones used in this paper). The

deposited semiconductor layers have usually thicknesses between 10-9

m and

2 × 10-7

m and contain in their base matrix certain chemical elements in order to

form type “p” and type “n” junctions. A photovoltaic cell is basically a p-n

junction. On their entire exterior surface, the photovoltaic cells are coated with

epoxy resins in order to provide a satisfying mechanical resistance to them but not

significantly affecting the entrance of the light in their volume. Usually,

photovoltaic cells are built having relatively small surfaces, providing small

quantities of electric current. By combining them in various serial or parallel

connections (photovoltaic cells batteries), their current/voltage can be increased in

order to be high enough for practical usability.

2. MATERIALS AND METHODS

The functional parameters (short circuit current, open circuit voltage,

external quantum efficiency) of four photovoltaic cells batteries exposed to gamma

radiation were studied with respect to the illuminance conditions and to the

absorbed dose values in order to determine which of them can be used in gamma

radiation dosimetry.

Three amorphous Si based low-power photovoltaic cells batteries were

exposed to a Co-60 gamma-ray source inside the “hot cells” found in

Radioisotopes and Radiation Metrology Department (DRMR) from Horia Hulubei

National Institute for Nuclear Physics and Engineering (IFIN-HH), ROMANIA, in

order to obtain three different well-known gamma radiation doses (33.45 kGy,

35.61 kGy and 37.9 kGy) and one was kept as blank (0 kGy). The Co-60 gamma

rays source provided a constant dose rate of 395 Gy/h at 10 cm distance from it, in

the place where the exposures were performed. The dose debit was measured using

3 Low-power photovoltaic cells batteries used as gamma radiation dose estimators Article no. 903

a 30006 type “Farmer” ionization chamber, a waterproof standard chamber for

absolute dosimetry (0.65 % combined standard uncertainty for a coverage factor

k = 2). The mean value of energies of the gamma rays emitted by a Co-60 source is

1.25 MeV, way higher than the bandgap energy of amorphous Si (a-Si), of

1.12 eV.

Each photovoltaic cells batteries was made of 12 photovoltaic cells

(connected in serial), placed on 2 rows of six cells, as it can be seen in Fig. 1. The

photovoltaic cells used in this paper were based on amorphous Si, which provide

increased sensitivity in low light conditions. The cells batteries had the following

characteristics: sensitive area – 12 cells × (6 × 10) × 10-6

m2, sensibility –

350 nA /lx, Vout/klx – 5v (idle voltage), Isc – 350 µA (short circuit current), r = 12

(number of p-n junctions/elementary cells in a battery).

Fig. 1 – Photovoltaic cells battery.

In order to locate each cell in a battery, a matrix approach was proposed,

meaning each battery was represented as a matrix with l lines and c columns

(l = 1…n, c = 1…m). A certain dose value corresponding to a certain cell can be

defined as Dl,c, if individual cell measurements are performed. These types of

individual cell measurements are important if gamma ray field uniformity studies

are performed [18].

In order to measure each of the functional parameters of the irradiated

photovoltaic cells batteries, an experimental device was built, as it can be seen in

Fig. 2.


Fig. 2 – Experimental set-up.

Practically, the experimental set-up was a dark box ((60 × 60 × 110) mm3)

containing the exposed photovoltaic cells batteries, a stabilized source of light and

a high quality electrometer. The source of light used was a multispectral

incandescent E10 type light bulb (6.3V, 2.0W). The illuminance inside the

experimental device was varied by modifying the voltage provided to the light

source. The voltages used were 2.1 V, 2.9 V, 3.7 V, 4.4 V and 5.2 V corresponding

to the following illuminance values: 33 lx ± 0.7 %, 79.8 lx ± 0.7 %, 196.8 lx ±

0.6 %, 422.3 lx ± 0.6 % and 813 lx ± 0.7 %. The illuminance measurements were

performed using a MOBILE-CASSY LD 524009 type lux-meter. For each of the

four photovoltaic batteries the currents in dark, Id, were measured: Id1 = 0.81 ×

10-9

A, Id2 = 1.4 × 10-9

A, Id3 = 1.48 × 10-9

A and Id4 = 0.1862 × 10-9

A.

When no light source is present, the electric current inside the short circuit is

the sum of the currents provided by the major and minor carriers. Locally, the

current is depending to the electric potential difference for each p-n junction, which

depends to the temperature.

When a light source is involved, on the exterior circuit of the photovoltaic

cells battery a photocurrent occurs [19–22], as follows (Equation 1):

fI

TBk

Vre

esII

]1

)0

(

[ (1)

where: I – electric current on the exterior circuit,

Is – saturation current of unirradiated p-n junctions,

If – photocurrent (photo-electric current),

V0 – electric potential difference for a p-n junction (open circuit),


e – electron change,

r – number of p-n junctions/elementary cells in a battery,

kB – Boltzmann constant,

T – temperature.

Short circuit current is increasing in a linear manner with the increase of the

intensity of the light. The intensity of the light source (incandescent light bulb,

multispectral emission) was modified by modifying the voltage to it. The obtained

photocurrent is practically proportional to illuminance.

By assigning the zero value to the electrical current thru the exterior circuit,

the expression of the electric potential difference (open circuit) for an r number of

p-n junctions (r × V0) is the following, Equation (2):

1ln

0sI

fI

e

kTVr . (2)

Equation (2) also shows the dependence between the electric potential

difference – open circuit voltage (V0) and the temperature. The influence of the

temperature was diminished as much as possible in the experiment performed in

this paper by using the photovoltaic cells batteries in current generator regime. This

way, the serial circuit of the p-n junctions is closed on a negligible resistance

related to the internal one, for which 00Vr . The short circuit current becomes

fI

shortI and it is not depending to the temperature anymore (ambient

temperature during experiment was 22 oC).

The dependence of the short circuit current value to the photovoltaic cell

parameters, dose, time and illuminance is given by the Equation (3), [23]:

)(

,

jLgelS

iR

jishortI

, (3)

where:

jishortI

,

– measured short-circuit current expressed in A,

t

iD

iR – dose rate (Di), expressed in Gy/s,

ApS – cross-section area expressed in m2,

l – minority-carrier diffusion length expressed in m,

ρ – density of the material (2330 kg/m3 for Si),

e – electronic charge (1.6 × 10-19

A s),


ε – average energy required to produce one electron-hole pair (5.76 ×

10- 19

J).

The Equation (3) becomes Equation (4):

)(81047.6

,jLglS

iD

jishortI

(4)

where:

g(Lj) – photo-generation rate,

Lj – illuminance expressed in lx.

The illuminance is expressed as follows, Equation (5):

LS

PCj

jL

, (5)

where:

Фj – luminance per lamp expressed in lm;

C – utilization coefficient;

P – light loss factor;

SL – area per lamp expressed in m2.

Equation (4) shows the linear dependence between short circuit current and

the absorbed dose, but also the influence of the illuminance.

For a photovoltaic cell, in normal functioning conditions, a very important

factor of its efficiency is the filling factor (FF). This factor is a measure of the

quality of a cell, and it is defined by determining its current-voltage characteristic.

The filling factor is dependent to the internal resistance of the photovoltaic cells

battery (FF is higher when the internal resistance is lower). Unlike the short-circuit

current, the open circuit voltage (V0) is not depending to the internal resistance of

the photovoltaic cells battery.

By exposing a photovoltaic cells battery to increasing gamma radiation dose,

its internal resistance is increasing, leading to a decreasing short circuit current.

This phenomenon is the base of the possibility of using photovoltaic cells battery

as instruments for gamma radiation doses estimations.

The evaluation of the absorbed dose is a very important task to be fulfilled,

especially in the cases of high dose values (> 100 Gy). In this direction, many

materials and devices were studied in order to determine their behaviour when

exposed to ionizing radiation [24]. As an example, the glass based dosimeters

showed their functionality on a wide range of absorbed dose values. Their usability

was proven in literature [25–28] by using various types of photo-spectrometric

measurements (optical densitometry). These types of dosimeters already showed

their potential in different fields as: applied physics experiments, nuclear medicine,

industry etc. [29–33].


In the case of photovoltaic cells batteries, their usability was shown for

higher energy gamma radiation (hundreds of keV) and for higher dose values.

Due to the fact that in this paper the short circuit current measurement was

performed (unaffected by temperature variations), its dependence to absorbed dose

is linear, as Equation (6) shows:

shortImn

fI

shortIfD )( , (6)

where: Ishort – short circuit photocurrent of photovoltaic cells battery ( 0shortI ),

n, m – fitting parameters.

In order to determine the variance associated to the estimated dose, the

Uncertainties Propagation Law is applied to Equation (6). In this case, the general

analytical relation is a function depending on three variables, D = D(If, n, m),

leading to Equation (7):

2

2

22

22

2

fI

fI

D

mm

D

nn

D

D

. (7)

The concrete form of Equation (7) is given by Equation (8), which contains

only known quantities:

222

222 m

fIf

ImnD

. (8)

By solving Equation (8), the uncertainty associated to a determined dose value can

be estimated using Equation (9):

2DD

. (9)

3. RESULTS AND DISCUSSIONS

The accumulation of radiation induced defects in the structure of irradiated

photovoltaic cells batteries is the cause of the reduction of their function

parameters. The graphical representation of functional parameters as a function of

absorbed dose value (i = 1, 2, 3, 4) and illuminance, Lj (j = 1, 2, 3, 4, 5), allows us

to determine the relation between them and to decide if any of them can be used as

dosimetric parameter.

In Fig. 3, the short circuit current as a function of illuminance, for each of

the four studied photovoltaic batteries, is presented.


Fig. 3 – Short circuit current as a function of illuminance, for each absorbed dose value.

As it can be seen from Fig. 3, the fitting relations have the following form,

Equation (10):

LbaI iishorti . (10)

It can also be seen that the short circuit absolute values are increasing with

the increase of the illuminance and are lower for higher absorbed dose values. As it

can be seen in Fig. 3, the square of the sample correlation coefficient (R2) takes

values over 94 % in all cases, showing the goodness of fits.

The variation of the open circuit voltage as a function of illuminance, for

each of the four studied photovoltaic batteries is shown in Fig. 4. It can be seen that

the open circuit voltage value is decreasing with the increase of the absorbed dose.

An increase of the open circuit voltage value with the increase of illuminance can

be also seen. For values of illuminance over 200 lx, a saturation effect is starting to

be observed.


Fig. 4 – Open circuit voltage as a function of illuminance, for each absorbed dose value.

The sensibility of photovoltaic cells batteries reported to absorbed dose and

illuminance are shown in Table 1.

Table 1

Sensibility of photovoltaic cells batteries reported to absorbed dose and illuminance

Sensibility [Gy/nA] 0.52 0.32 0.21 0.12 0.11

Illuminance [lx] 33.0 79.8 196.8 422.3 813.0

From Table 1 in can be observed that with the increase of the illuminance a

lower dose value is needed to obtain a nA of short circuit current, meaning an

increased sensibility [34]. A saturation trend can also be observed, starting from

around a 422.3 lx illuminance value. Table 1 also shows that the five illuminance

values chosen in this paper are optimal.

The variation of the external quantum efficiency with illuminance, for each

absorbed dose value, η (%), is presented in Fig. 5. The external quantum efficiency

represents the fraction of the incident light that is converted in electrical energy,

and it is given by Equation (11):


100

,

0,

,

jiP

ijV

jishortI

ji

(11)

where Pi represents the power of the optical radiation reaching the surface of the

photovoltaic sensor.

Fig. 5 – External quantum efficiency as a function of illuminance, for each absorbed dose value.

From Fig. 5 it can be seen that with the increased of the absorbed dose value,

a decrease of the efficiency of the battery is occurring. For the studied photovoltaic

cells batteries, the external quantum efficiency was placed between 0.2 % and

1.8 %, on the entire range of artificial illuminating conditions. The external

quantum efficiency in artificial illuminating conditions is inferior to the one

provided by Sun, (5–7) %.

From the three functional parameters studied, the one chosen to be used as

dosimetric parameter was the short circuit current, due to the fact that it is not

affected by other external parameters as the temperature. In Fig. 6, the variation of

the short circuit current with the absorbed dose value, on the entire doses range is

presented.


Fig. 6 – Short circuit current as a function of absorbed dose, for each illuminance conditions.

As it can be seen in Fig. 6, the short circuit current absolute value is

decreasing with the increase of the absorbed dose value and increasing with the

increase of illuminance. For a certain illuminance value, the analytical relation

between the short circuit current and absorbed dose is a relation of the type of

Equation (6).

Short circuit current as a function of absorbed dose, for each illuminance

conditions on the (0–35.61) kGy interval is presented in Fig. 7. This interval was

chosen for its higher linearity.

By using the fitting relations from Fig. 7, the analytical relations between the

absorbed dose and short circuit current, for each illuminance conditions, were

determined (calibration curves). The results are presented in Table 2.

Table 2

Analytical relations between absorbed dose and short circuit current on (0–35.61) kGy interval

Calibration curve

for each illuminance value

Ishort

for (0–35.61) kGy interval

[A] × 10-5

Illuminance

[lx]

R2

[%]

D1 [kGy] = 333.3 + 1.6 × 107 × Ishort (–2.06) ÷ (–1.75) 33.0 64.8

D2 [kGy] = 341.7 + 4.2 × 106 × Ishort (–8.1) ÷ (–7.0) 78.9 75.2

D3 [kGy] = 366.7 + 3.3 ×106 × Ishort (–11.1) ÷ (–9.7) 196.8 73.1

D4 [kGy] = 383.0 + 2.1 × 106 × Ishort (–18.0) ÷ (–16.0) 422.3 88.0

D5 [kGy] = 280.0 + 106 × Ishort (–27.8) ÷ (–24.0) 813.0 99.6


Fig. 7 – Short circuit current as a function of absorbed dose (0–35.61) kGy,

for each illuminance conditions.

By measuring the short circuit value and using the relations from Table 2

according to the chosen illuminance conditions, an unknown absorbed dose value

can be determined. These relations are valid only on the studied (0–35.61) kGy

interval due to the fact that the calibration “short circuit current – absorbed dose”

was performed only on this interval. Having more dose values spread on a larger

interval, new calibration curves can be obtained. As it can be seen from R2 values,

the calibration curve corresponding to the 813.0 lx illuminance fits best the

experimental points due to the fact this value is closest to the one recommended by

the producer of this type of photovoltaic cells batteries (working regime).

4. CONCLUSIONS

In this paper, the functional parameters (short circuit current, open circuit

voltage, external quantum efficiency) of low-power photovoltaic cells batteries after

their exposure to gamma radiation were studied. It was shown that all of these

parameters are affected by the energy deposited in their volume. Do to this fact, it

was shown that low-power photovoltaic cells batteries can be used as sensor in


gamma radiation dosimetry. It was also determined which of these parameters is

the best parameter to be use in dosimetry. The best parameter to be use in

dosimetry was found to be the short circuit current.

By studying the short circuit current variation with the absorbed dose value,

calibration curves were obtained. Using these calibration curves, any unknown

dose value can be determined. The calibration curves are valid only on the studied

(0–35.61) kGy interval due to the fact that the calibration “short circuit current –

absorbed dose” was performed only on this interval. Having more dose values

spread on a larger interval, new calibration curves can be obtained.

The uncertainty associated to the proposed gamma radiation dosimetry

method was also estimated. The main qualities of this dosimetry method are that it

is fast, easy to be applied in various situations and economically efficient.

REFERENCES

1. M.-R. Ioan, Investigation of RGB spectral components in the images captured through gamma

rays affected optical focusing lens, Rom. J. Phys. 61 (7-8), 1198-1206 (2016).

2. M.-R. Ioan, Study of the optical absorption coefficient variation in soda-lime and borosilicate

glasses due to their exposure to gamma-rays, Rom. J. Phys. 62 (3-4), 206 (2017).

3. D. Nikolic and A. Vasic-Milovanovic, The impact of successive gamma and neutron irradiation

on characteristics of PIN photodiodes and phototransistors, W A. Monteiro (Editor), Radiation

Effects in Materials, InTech, 2016, doi: 10.5772/62756.

4. M.-R. Ioan, Study of the optical materials degradation caused by gamma radiation and the

recovery process by controlled heat treatment, Rom. J. Phys. 61 (5-6), 892-902 (2016).

5. M.-R. Ioan, Analyzing of the radiation induced damage to optical glasses by using online heating

laser measurements, Rom. J. Phys. 61 (3-4), 614-625 (2016).

6. A.V. Kir’yanov, Effects of electron irradiation upon absorptive and fluorescent properties of

some doped optical fibers, W A. Monteiro (Editor), Radiation Effects in Materials, InTech, 2016,

doi: 10.5772/63939.

7. M.R. Ioan, I. Gruia, G.V. Ioan, L. Rusen and P. Ioan, Laser beam used to measure and highlight

the transparency changes in gamma irradiated borosilicate glass, J. Optoelectron. Adv. M. 16

(1-2), 162-169 (2014).

8. M.-R. Ioan, I. Gruia, G-V. Ioan, L. Rusen, C.D. Negut and P. Ioan, The influence of gamma rays

and protons affected optical media on a real Gaussian laser beam parameters, Rom. Rep. Phys.

67 (2), 508-522 (2015).

9. M.R. Ioan and I. Gruia, Change of optical parameters of the BK-7 glass substrate under gamma

irradiation, Rom. J. Phys. 60 (9-10), 1515-1524 (2015).

10. S. V. Firstov, V. F. Khopin, S. V. Alyshev, E. G. Firstova, K. E. Riumkin, M. A. Melkumov, A.

M. Khegai, P. F. Kashaykin, A. N. Guryanov and E. M. Dianov, Effect of gamma-irradiation on

the optical properties of bismuth-doped germanosilicate fibers, Optical Materials Express 6 (10),

3303-3308 (2016).

11. J. M. Pearce, N. Podraza, R. W. Collins, M. M. Al-Jassim, K. M. Jones, J. Deng and C.R.

Wronski, Optimization of open circuit voltage in amorphous silicon solar cells with mixed-phase

(amorphous+nanocrystalline) p-type contacts of low nanocrystalline content, J. Appl. Phys. 101

(11) 114301 (2007), doi:10.1063/1.2714507.

12. Solar Cell, https://en.wikipedia.org/wiki/Solar_cell.

https://en.wikipedia.org/wiki/Solar_cell


13. N. Kavasoglu, A. S. Kavasoglu, O. Birgi and S. Oktik, Intensity modulated short circuit current

spectroscopy for solar cells, Sol. Energy. Mater. Sol. 95, 727-730 (2011).

14. C. Ciobotaru and G. Musa, Monochromatization effect kinetic model for Penning gas mixtures

emission mechanisms, Turk. J. Phys. 36 (1), 77-85 (2012), doi: 10.3906/fiz-1010-4.

15. L. C. Ciobotaru, Monochromatisation effect - AC/DC discharges comparative behaviour,

Rom. Rep. Phys. 62 (1), 134-141 (2010).

16. L. Ciobotaru, P. Chiru, C. C. Neacsu, G. Musa, PDP type barrier discharge ultraviolet radiation

source, J. Optoelectron. Adv. M. 6 (1), 321-324 (2004).

17. J. Perlin, From space to Earth: the story of solar electricity, Earthscan 50, 1999.

18. M. -R. Ioan, A novel method involving Matlab coding to determine the distribution of a collimated

ionizing radiation beam, J. Instrum. 11, P08005 (2016), doi: 10.1088/1748-0221/11/08/P08005.

19. H.M. Diab, A. Ibrahim, and R. ElMallawany, Silicon Solar Cells as a Gamma Ray Dosimeter,

Measurement 46 (9), 3635–3639 (2013).

20. D. Renker and E. Lorenz, Advances in solid state photon detectors, J. Instrum. 4, P04004 (2009).

21. I. Gaye, R. Sam, A. D. Sere, I. F. Barro, M. A. Ould EI Moujtaba, R. Mane and G. Sissoko, Effect

of irradiation on the transient response of a silicon solar cell, I.J.E.T.T.C.S. 1 (3) 210-214

(2012).

22. K. Scharf and J. K. Sparrow, Steady-state response of silicon radiation detectors of the diffused p-

n junction type to X-ray. I photovoltaic mode of operation, Journal of Research of the National

Bureau of Standards -A Physics and Chemistry 68A (6) (1964).

23. K. Scharf, Photovoltaic effect produced in silicon solar cells by X-and gamma rays, Journal of

Research of the National Bureau of Standards-A. Physics and Chemistry 64A (4), 297-307

(1960).

24. A.C. Muller, F. X. Rizzo and L. Galanter, Solar cell integrating dosimeter, BNL 902 (T-368) –

Isotopes-Industrial Technology – TID-4500, 37th Ed, 1964.

25. John F. Fowler, Solid State Dosimetry, Phys. Med. Biol. 8 (1), 1-32 (1963).

26. Sh. Makhkamov, R.A. Muminov, M. Karimov, N. A. Tursunov and A. R. Sattiev, Influence of the

conductivity type of silicon on the process of radiation degradation of solar cells, Appl. Sol.

Energ. 49 (2), 62-66 (2013).

27. M.-R. Ioan, Amorphous and crystalline optical materials used as instruments for high gamma

radiation doses estimations, Nucl. Instrum. Meth. B 377, 43-49 (2016), doi:

10.1016/j.nimb.2016.04.009.

28. P.E. Asard and G. Baarsen, Commercial photodiodes as gamma and Roentgen ray dosimeters,

Acta. Radiol. Ther. Phy. 7, 47-57 (1968).

29. M.R. Ioan, LIDT test coupled with gamma radiation degraded optics, Opt. Commun. 369, 94-99

(2016), doi: 10.1016/j.optcom.2016.02.031.

30. M.R. Ioan, Matlab fractal techniques used to study the structural degradation caused by alpha

radiation to laser mirrors, Nucl. Instrum. Meth. A 877, 131-137 (2018), doi:

10.1016/j.nima.2017.09.037.

31. I.R. Edmonds, U. Rajappa, C. Hirst and P. Rowntree, Photovoltaic cells for low energy x-ray

dosimetry, Phys. Med. Biol. 35 (4), 571-578 (1990).

32. M.R. Ioan, I. Gruia, P. Ioan, M. Bacalaum, G–V. Ioan and C. Gavrila, 3 MeV protons to simulate

the effects caused by neutrons in optical materials with low metal impurities, J. Optoelectron.

Adv. M. 15 (5-6), 523-529 (2013).

33. H. Diab, A. Ibrahim and R. Elmallawany, Dosimetric study of monocrystalline silicon solar cell,

Rom. J. Biopys. 22 (2), 125-133 (2012).

34. L. Done and M-R. Ioan, Minimum Detectable Activity in gamma spectrometry and its use in low

level activity measurements, Appl. Radiat. Isotopes 114, 28-32 (2016), doi:

10.1016/j.apradiso.2016.05.004.

low-power photovoltaic cells batteries used as … · 3 low-power photovoltaic cells batteries used...

Documents