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Mini and micro transducers for Mössbauer spectroscopy
Nuclear Instruments
*H CL
and Methods in Physics Research B 95 (1995) 278-280
k!l[IMl B
Beam Interactions with Materials 6 Atoms
Letter to the Editor
ELSEYIER
Mini and micro transducers for Mijssbauer spectroscopy V.A. Evdokimov
a, M. Mashlan b,*, D. Zak b, A.A. Fyodorov O.V. Misevich a
a, A.L. Kholmetskii
a,
aFaculty of Physics, Belorussian State Unioersiry 4 Skoriny Au., 220 080 Minsk, Belarus b Department of Experimental Physics, Palacky University, Soobody 26, 771 46 Olomouc, Czech Republic Received 19 April 1994; revised form received 22 November
1994
Abstract Two transducers with polyamide fibres as suspension brackets are described in this paper. The mini transducer uses barium ferrite magnets and its weight is 360 g, whereas the micro transducer uses SmCo, magnets and its weight is 36 g. An integral nonlinearity of the velocity scale better than 0.07% was obtained in experiments with the mini transducer and 0.11% with the micro transducer. Both transducers have been in use since 1992.
The electromechanical drives of double-loudspeaker type with velocity feedback [l] are used in MGssbauer spectroscopy most frequently. Miniature designs of an electromechanical drive have been described in the last few years [2-41. Mini and micro transducers of double-loudspeaker type described in this paper are characterised by 360 and 36 g weights, 48 and 22 mm diameters and 62 and 34 mm lengths, respectively. Barium ferrite magnets are used in the mini transducer. The micro transducer uses SmCo, magnets. Weights of the moving parts without radiation source are 6.5 and 1.2 g, respectively. The drive coil of the mini transducer is made of copper wire (diameter 0.07 mm). The resistance of the drive coil is about 50 fl. The velocity pickup coil of this transducer is made of 0.05 mm diameter copper wire and its resistance is about 230 R. The micro transducer has a drive coil made of 0.07 mm diameter copper wire with a resistance of about 50 a. The velocity pickup coil of micro transducer is made of 0.05 mm diameter copper wire and its resistance is about 120 n. Fig. 1 shows the fixing of the drive rod by polyamide threads. The transducer amplitude and phase frequency characteristics are shown in Figs. 2 and 3. Resonance frequencies of mini and micro transducers obtained were about 35 and 86 Hz without radiation source, respectively. It is well known, that the main resonance depends on the total mass of the moving part. Fig. 4 shows its response to the mass of the moving part. Fig. 5 shows the schematic circuit diagram of the
fibre
case Fig. 1. The arrangement
of drive rod fixing by polyamide
control drive unit, which is used with both velocity transducers. This control unit consists of the amplifier of the velocity pickup coil signal (Al), the summator of the
two
1 ..*. mim
T
m
.
micm .
. I
04 10
..,,..: 100
......:
Corresponding
author.
0168-583X/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0168-583X(94)0063 l-3
“.....:
,000 fmq”.“sy
l
fibre.
“...d lOOO0
(liz,
Fig. 2. The amplitude frequency
characteristics.
100000
VA Evdok~o~
t
et al. /Nucl.
279
Ins&. and Me& in Phys. Res. B 95 (I 995) 278-280
I
-180 _
0 0.00
.:.:.:.:.:.:.:.:? 2.w
4.00
Fig. 3. The phase frequency characteristics.
6.00
8.00
IO,00
12.00
11.00
18.00
mau of drive rod [g,
fmqwncy [Hz]
Fig. 4. The response of resonance frequency to the mass of the drive rod.
reference velocity and velocity pickup coil signal (AZ), the integrator of the velocity pickup coil signal (A4), which is used for correcting the error signal, the summator of the error signal with fist integral of the velocity pickup coil signal fA3), the PID-controller (A@, the integrator for correction of the dc signal (As) and the power amplifier with local feedback (A7, Tl, T2). The amplitude and phase frequency characteristics of this control unit are adjusted for the specific transducer. The chronology of the correction of those characteristics is as follows. The regulation of the threshold frequency and the amplification coefficient of the PID-controller is realised. After the adjustment of the amplification coefficient to its maximal value, the min~isation of the error signal is made by the addition of a part of the first integral of the velocity pickup coil signal and a part of the reference velocity signal to the error signal 151.The error signal value of about O.OS-0.03% of the velocity signal can be obtained by means of this control system.
As an indirect estimation of the performance of the equipment, various well-known Mijssbauer spectra were measured repeatedly in constant acceleration regime with a symmetrical velocity signal. The spectra were registrated in 1024 channels. The frequencies of the velocity signals have been 28 and 84 Hz for mini and micro transducers respectively. The radiation source 57Co(Rh) with a mass of 530 mg was used for an estimation of the equipments. The main parameter characterising the quality of a Mijssbauer spectrometer is the nonlinearity of the velocity scale. The following algorithm was used for an estimation of the nonlinearity. The spectral lines of the natural iron Massbauer spectra were approximated by Lorentz functions. The nonlinearity for all line positions was calculated by means of fitting the experimental position of the spectral lines to its theoretical positions by a least squares
Fig. 5. Schematiccircuit diagramof the control drive unit.
V.A. Elldokimot, et al. /Nucl.
280
lnstr. and Meth. in Phys. Res. B 95 (1995) 278-280
Table 1
mini transducer micro transducer
i
1
2
3
4
5
6
.x(i) [mm/s] non(i) [i] x(i) [mm/s] non(i) [%J
- 5.049 0.06 - 5.037 -0.10
- 2.809 -0.01 - 2.822 0.08
-0.571 - 0.05 - 0.584 0.07
1.105 - 0.04 1.102 0.01
3.336 - 0.01 3.339 - 0.01
5.567 0.06 5.580 - 0.05
method and by means of the relation
x(i) non(i)
=
- ac( i) - b
46)
- ~(1)
’
i (i = 1 to 6), x(i), u(i), a, b are line number, experimental position of the line, theoretical position of the Iine, and parameters from the least squares method, respectively. The unfolded spectrum was used for the qualitative test of the equipment. The experimental positions of lines and its nonlinearities are shown in Table 1. The velocity ranges are +70 mm/s and k30 mm/s for mini and micro transducers, respectively. where
References [l] E. Kankeleit, Rev. Sci. Instr. 35 (1964) 194. [2] D.G. Agresti, R.V. Morris, E.L. Wills. T.D. Shelver. M.M. Pimperl. M. Shen, B.C. Clark, B.D. Ramsey, Hyperfine Interactions 72 (1992) 285. [3] G. KlingeIh~fer, J. Foh, P. Held, H. Jsger, E. Kankeleit, R. Teucher, Hyperfine Interactions 71 (1992) 1449. [4] A.L. Khoimetskii, V.A. Evdokimov, O.V. Misevich, A.A. Fedorov, A.R. Lopatik. M. Mashlan, D. &k, V. Snasel, lCAME’93, Vancouver, Canada, 1993, Book of Abstracts, 7-19A. [5] V.A. Evdokimov, Y.G. Kononov, A.S. Lobko, A.A. Fyodorov, instrum. Exp. Tech. 29 (19861297.
*H CL
and Methods in Physics Research B 95 (1995) 278-280
k!l[IMl B
Beam Interactions with Materials 6 Atoms
Letter to the Editor
ELSEYIER
Mini and micro transducers for Mijssbauer spectroscopy V.A. Evdokimov
a, M. Mashlan b,*, D. Zak b, A.A. Fyodorov O.V. Misevich a
a, A.L. Kholmetskii
a,
aFaculty of Physics, Belorussian State Unioersiry 4 Skoriny Au., 220 080 Minsk, Belarus b Department of Experimental Physics, Palacky University, Soobody 26, 771 46 Olomouc, Czech Republic Received 19 April 1994; revised form received 22 November
1994
Abstract Two transducers with polyamide fibres as suspension brackets are described in this paper. The mini transducer uses barium ferrite magnets and its weight is 360 g, whereas the micro transducer uses SmCo, magnets and its weight is 36 g. An integral nonlinearity of the velocity scale better than 0.07% was obtained in experiments with the mini transducer and 0.11% with the micro transducer. Both transducers have been in use since 1992.
The electromechanical drives of double-loudspeaker type with velocity feedback [l] are used in MGssbauer spectroscopy most frequently. Miniature designs of an electromechanical drive have been described in the last few years [2-41. Mini and micro transducers of double-loudspeaker type described in this paper are characterised by 360 and 36 g weights, 48 and 22 mm diameters and 62 and 34 mm lengths, respectively. Barium ferrite magnets are used in the mini transducer. The micro transducer uses SmCo, magnets. Weights of the moving parts without radiation source are 6.5 and 1.2 g, respectively. The drive coil of the mini transducer is made of copper wire (diameter 0.07 mm). The resistance of the drive coil is about 50 fl. The velocity pickup coil of this transducer is made of 0.05 mm diameter copper wire and its resistance is about 230 R. The micro transducer has a drive coil made of 0.07 mm diameter copper wire with a resistance of about 50 a. The velocity pickup coil of micro transducer is made of 0.05 mm diameter copper wire and its resistance is about 120 n. Fig. 1 shows the fixing of the drive rod by polyamide threads. The transducer amplitude and phase frequency characteristics are shown in Figs. 2 and 3. Resonance frequencies of mini and micro transducers obtained were about 35 and 86 Hz without radiation source, respectively. It is well known, that the main resonance depends on the total mass of the moving part. Fig. 4 shows its response to the mass of the moving part. Fig. 5 shows the schematic circuit diagram of the
fibre
case Fig. 1. The arrangement
of drive rod fixing by polyamide
control drive unit, which is used with both velocity transducers. This control unit consists of the amplifier of the velocity pickup coil signal (Al), the summator of the
two
1 ..*. mim
T
m
.
micm .
. I
04 10
..,,..: 100
......:
Corresponding
author.
0168-583X/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved SSDI 0168-583X(94)0063 l-3
“.....:
,000 fmq”.“sy
l
fibre.
“...d lOOO0
(liz,
Fig. 2. The amplitude frequency
characteristics.
100000
VA Evdok~o~
t
et al. /Nucl.
279
Ins&. and Me& in Phys. Res. B 95 (I 995) 278-280
I
-180 _
0 0.00
.:.:.:.:.:.:.:.:? 2.w
4.00
Fig. 3. The phase frequency characteristics.
6.00
8.00
IO,00
12.00
11.00
18.00
mau of drive rod [g,
fmqwncy [Hz]
Fig. 4. The response of resonance frequency to the mass of the drive rod.
reference velocity and velocity pickup coil signal (AZ), the integrator of the velocity pickup coil signal (A4), which is used for correcting the error signal, the summator of the error signal with fist integral of the velocity pickup coil signal fA3), the PID-controller (A@, the integrator for correction of the dc signal (As) and the power amplifier with local feedback (A7, Tl, T2). The amplitude and phase frequency characteristics of this control unit are adjusted for the specific transducer. The chronology of the correction of those characteristics is as follows. The regulation of the threshold frequency and the amplification coefficient of the PID-controller is realised. After the adjustment of the amplification coefficient to its maximal value, the min~isation of the error signal is made by the addition of a part of the first integral of the velocity pickup coil signal and a part of the reference velocity signal to the error signal 151.The error signal value of about O.OS-0.03% of the velocity signal can be obtained by means of this control system.
As an indirect estimation of the performance of the equipment, various well-known Mijssbauer spectra were measured repeatedly in constant acceleration regime with a symmetrical velocity signal. The spectra were registrated in 1024 channels. The frequencies of the velocity signals have been 28 and 84 Hz for mini and micro transducers respectively. The radiation source 57Co(Rh) with a mass of 530 mg was used for an estimation of the equipments. The main parameter characterising the quality of a Mijssbauer spectrometer is the nonlinearity of the velocity scale. The following algorithm was used for an estimation of the nonlinearity. The spectral lines of the natural iron Massbauer spectra were approximated by Lorentz functions. The nonlinearity for all line positions was calculated by means of fitting the experimental position of the spectral lines to its theoretical positions by a least squares
Fig. 5. Schematiccircuit diagramof the control drive unit.
V.A. Elldokimot, et al. /Nucl.
280
lnstr. and Meth. in Phys. Res. B 95 (1995) 278-280
Table 1
mini transducer micro transducer
i
1
2
3
4
5
6
.x(i) [mm/s] non(i) [i] x(i) [mm/s] non(i) [%J
- 5.049 0.06 - 5.037 -0.10
- 2.809 -0.01 - 2.822 0.08
-0.571 - 0.05 - 0.584 0.07
1.105 - 0.04 1.102 0.01
3.336 - 0.01 3.339 - 0.01
5.567 0.06 5.580 - 0.05
method and by means of the relation
x(i) non(i)
=
- ac( i) - b
46)
- ~(1)
’
i (i = 1 to 6), x(i), u(i), a, b are line number, experimental position of the line, theoretical position of the Iine, and parameters from the least squares method, respectively. The unfolded spectrum was used for the qualitative test of the equipment. The experimental positions of lines and its nonlinearities are shown in Table 1. The velocity ranges are +70 mm/s and k30 mm/s for mini and micro transducers, respectively. where
References [l] E. Kankeleit, Rev. Sci. Instr. 35 (1964) 194. [2] D.G. Agresti, R.V. Morris, E.L. Wills. T.D. Shelver. M.M. Pimperl. M. Shen, B.C. Clark, B.D. Ramsey, Hyperfine Interactions 72 (1992) 285. [3] G. KlingeIh~fer, J. Foh, P. Held, H. Jsger, E. Kankeleit, R. Teucher, Hyperfine Interactions 71 (1992) 1449. [4] A.L. Khoimetskii, V.A. Evdokimov, O.V. Misevich, A.A. Fedorov, A.R. Lopatik. M. Mashlan, D. &k, V. Snasel, lCAME’93, Vancouver, Canada, 1993, Book of Abstracts, 7-19A. [5] V.A. Evdokimov, Y.G. Kononov, A.S. Lobko, A.A. Fyodorov, instrum. Exp. Tech. 29 (19861297.