- Email: [email protected]
Novel glass ceramic-type micropattern gas detector with PEG3C
Nuclear Instruments and Methods in Physics Research A 732 (2013) 273–276
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research A journal homepage: www.elsevier.com/locate/nima
Novel glass ceramic-type micropattern gas detector with PEG3C Fuyuki Tokanai a,n, Toru Moriya a, Mirei Takeyama a, Hirohisa Sakurai a, Shuichi Gunji a, Takashi Fushie b, Hajime Kikuchi c, Takayuki Sumiyoshi d, Hirioyuki Sugiyama e, Teruyuki Okada e, Noboru Ohishi e, Syunji Kishimoto f, Hideki Hamagaki g a
Department of Physics, Yamagata University, Yamagata 990-8560, Japan PEG Project Blanks Division, HOYA CORPORATION, Tochigi 321-4292, Japan c HOYA CORPORATION, Yamanashi 408-8550, Japan d Graduate School of the Faculty of Science and Engineering, Tokyo Metropolitan University, Tokyo 192-0397, Japan e Electron Tube Division, Hamamatsu Photonics K.K., Shizuoka 438-0193, Japan f Institute of Material Structure Science, KEK, Tsukuba 305-0801, Japan g Center for Nuclear Study, Graduate School of Science, the University of Tokyo, Saitama 351-0198, Japan b
art ic l e i nf o
a b s t r a c t
Available online 9 August 2013
A new glass plate (GP) has been developed for a hole-type micropattern gas detector (MPGD). The material of the GP is a crystallized photosensitive etching glass (PEG3C) made by Hoya Corporation. A basic performance test of the hole-type MPGD was carried out using an X-ray beam with Ne-based gas mixtures at 1 atm. Gains of up to 5 103 and 6 104 were obtained using a single and a double GP, respectively. An energy resolution of 17% was obtained for 6 keV X-rays with a single GP. It was also shown that there is little charging-up effect in the GP. In this paper, we report the characteristics of the new hole-type MPGD with a GP made of PEG3C. & 2013 Elsevier B.V. All rights reserved.
Keywords: Gaseous PMT Glass ceramic plate Micropattern gas detector
1. Introduction Since the invention of the microstrip gas detector by Oed [1], various types of gaseous detectors with high granularity, referred to as micropattern gas detectors (MPGDs) [2–4], have emerged and been widely used in various fields. At present, one of the most popular and useful MPGDs is the hole-type MPGD, as typified by the gas electron multiplier (GEM) [4]. A hole-type MPGD typically consists of a thin insulator sheet (0.05–2 mm thick) with a large number of small holes (0.01–1 mm diameter). The main applications and the development of the GEM have been reviewed in the literature [5]. A glass capillary is another popular hole-type MPGD. The insulator is a lead glass or a Pyrex glass, and the holes are made by employing the standard manufacturing process for a microchannel plate (MCP) [2,6] or using a microblasting technique [7]. The glass material of the MPGD is very promising for the development of a neutron detector and of a gaseous photomultiplier tube (PMT) for visible light. 3He gas is used as the neutron converter in the gas detector. However, the high cost of the 3He gas makes it impractical to flush 3He gas through the detector during a long operation. 3He is suitable for use in a sealed neutron detector, because the low outgassing from the glass renders possible for the detector to operate with a good long-term stability [8]. n
Corresponding author. Tel.: +81 236284554. E-mail address: [email protected] (F. Tokanai)
0168-9002/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.nima.2013.08.001
In the case of a gaseous PMT with a bialkali photocathode that is sensitive to visible light, attention must be paid to the high chemical activity of the bialkali metal. By investigating the process of production for a bialkali photocathode in the gaseous PMT, we found that a glass is a more suitable material for the hole-type MPGD than the material of Kapton used in GEMs [9]. Recently, Takahashi and co-workers at the University of Tokyo have generated new interest in a glass GEM with a photosensitive etching glass (PEG) developed by Hoya Corporation (Tokyo, Japan) [10]. Following the successful operation of their glass GEM, we have developed another hole-type MPGD using a new glass ceramic plate, made of a crystallized photosensitive etching glass (PEG3C). In this paper, we describe the characteristics of the novel hole-type MPGD with a PEG3C glass plate. 2. PEG3C as a new material for MPGDs Photosensitive glass is a special glass that allows to form microstructures in the glass using a standard photolithographic method. The glass can be utilized for glass circuit boards used in ink-jet printer heads, in micro-electro-mechanical systems (MEMSs), and in flatpanel displays. Here, we use the crystallized photosensitive etching glass PEG3C developed by Hoya Corporation as a new material for MPGDs. Fig. 1 shows the standard manufacturing process of the hole-type MPGD with a glass plate (GP) made of PEG3C. A
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F. Tokanai et al. / Nuclear Instruments and Methods in Physics Research A 732 (2013) 273–276
photosensitive glass substrate is prepared. It is then exposed to ultraviolet (UV) light through a photomask. When the glass is heated to about 600 1C in an oven, the UV-exposed region is crystallized. After forming the exposed crystallized part, a diluted hydrofluoric acid is sprayed onto the front and rear surfaces to form through holes. Then the entire substrate with the formed through holes is again irradiated with UV light. The substrate is then heated to 1100 1C to crystallize the glass. Finally, both sides of the glass are metallized with Cu and Cr of 1 μm thickness to form the electrodes of the MPGD. The GPs made of PEG3C are shown in Fig. 2. Fig. 2(a) shows the First Prototype GP with a thickness of 150 μm and an effective diameter of 20 mm. A GP with a large effective area, a square with 100 mm side length, is shown in Fig. 2(b). The First Prototype GP has holes with a diameter of 100 μm and a pitch between the holes of 360 μm (Fig. 2(c)). Fig. 2(d) shows part of a GP with fine holes of 50 μm diameter and 70 μm pitch produced with the current manufacturing process.
3. Basic performance of the GP made of PEG3C In the following performance test, we studied the First Prototype GP made of 150 μm thick PEG3C with an effective diameter of 20 mm, and with holes having a diameter and a pitch of 100 μm and 360 μm, respectively.
1. Glass substrate
2. UV exposure
3.1. Single operation of the hole-type MPGD Fig. 3(a) shows the experimental setup used to investigate the basic performance of the hole-type MPGD with the GP made of PEG3C. The gas gain and the energy resolution were estimated for Ne-based gas mixtures at 1 atm using the X-ray beam at the beamline BL-14A of the Photon Factory in the High Energy Accelerator Research Organization (KEK-PF). The energy of the incident X-ray beam was fixed at 6 keV using a Si double-crystal monochromator. The incident X-rays were defined using a collimator of 0.1 mm diameter. The flux was controlled by adjusting the thickness of the Cu foils installed behind the collimator. The absorption region for the X-rays (drift region) is 5 mm deep between the mesh window and the top of the GP. The induction region between the bottom of the GP and the anode plate has a thickness of 2 mm. The electric fields in the drift and induction regions are set to be 100 V/cm and 1000 V/cm, respectively. Fig. 4 shows the effective gains for the gas mixtures Ne (90%) + CF4 (10%) and Ne (90%) + i-C4H10 (10%) at 1 atm as a function of the voltage across the GP electrodes. The gain values were obtained by measuring the amplitude of the charge output from the anode plate using a digital oscilloscope. Gains of up to 5 103 were safely achieved using a single GP for both gas mixtures. The typical pulse height spectrum in the case of using 6 keV X-rays is shown in Fig. 5 for a gas gain of 3000. The energy resolution is 17%, which is equal to the value obtained using a hole-type MPGD with a glass capillary plate [11]. Fig. 6 shows the dependencies of the gas gain and energy resolution of the MPGD on the X-ray beam intensity. The beam intensity is in the range from 87 to 9962 counts/s, which corresponds to a beam rate per unit area from 1.1 104 to 1.3 106 counts/s/mm2, derived by dividing the beam intensity by the area of the beam collimator with a diameter of 0.1 mm. The relative gains are normalized by the peak ADC channel obtained at a beam rate of 87 counts=s. The relative gain decreases by 5% and the energy resolution deteriorates by 0.6% when the beam intensity is increased to 9962 counts/s. These results show that the charging-up effect of the MPGD is negligible at a beam rate per unit area of 1.3 106 counts/s/mm2. 3.2. Tandem operation of the hole-type MPGD
3. Crystal formation
4. Via etching
5. UV exposure
6. Crystal formation
7. Metalization (Cu / Cr electrode) Fig. 1. Manufacturing process of a hole-type MPGD with a glass plate made of crystallized photosensitive etching glass (PEG3C) developed by Hoya Corporation.
A schematic view of the tandem operation with a double GP is shown in Fig. 3(b). The absorption region for the X-rays (drift region) is again 5 mm deep. The induction region, defined between the upper GP and the lower GP, has a thickness of 2 mm. The transfer region between the bottom of the lower GP and the anode plate is 1 mm thick. The same applied voltage was set for both GPs ðΔV GP Þ throughout the entire measurements. The effective gain was measured by the current mode using an X-ray beam from an X-ray generator, similarly to previous studies [12,13]. Fig. 7 shows the effective gain of the double GP for the Ne (90%) + CF4 (10%) gas mixture at 1 atm as a function of the voltage applied between the electrodes of each GP. The gain of each single GP is also plotted in the figure for comparison. We could achieve a gain of up to 6 104 for the selected gas mixture. The pulse height spectrum in the case of using 6 keV X-rays is shown in Fig. 8 for a gas gain of 10,000. The energy resolution is 20%, which is slightly degraded compared with that obtained using a single GP.
4. Conclusion We reported a new hole-type MPGD with a glass plate (GP) made of a crystallized photosensitive etching glass (PEG3C) developed by Hoya Corporation. PEG3C is expected to be a suitable
F. Tokanai et al. / Nuclear Instruments and Methods in Physics Research A 732 (2013) 273–276
275
Fig. 2. Photographs of GPs made of PEG3C: (a) First Prototype GP with a thickness of 150 μm and an effective diameter of 20 mm; (b) large GP with an effective area of 100 mm 100 mm; (c) scanning electron microscope (SEM) image of the First Prototype GP with holes having a diameter and a pitch of 100 μm and 360 μm, respectively; (d) SEM image of part of a fine-pitch GP with holes having a diameter and a pitch of 50 μm and 70 μm, respectively.
6 keV X-ray
Ne(90%)+i-C4H10(10%)
104
Vcathode
Mesh
Ne(90%)+CF4(10%)
5 mm VGP1_out
2 mm Anode plane
ORTEC 142PC
103
6 keV X-ray Mesh
Vcathode 5 mm VGP1_in
PEG3C_1
VGP1_out
2 mm
460
480
500
520 540 Δ VGP [V]
560
580
600
Fig. 4. Gain of the GPs made of PEG3C, for the gas mixtures Ne (90%) + CF4 (10%) and Ne (90%) + i-C4H10 (10%) at 1 atm as a function of the voltage across the GP electrodes obtained with 6 keV X-rays.
VGP2_in
PEG3C_2 Anode plane
Gain
VGP1_in
PEG3C
VGP2_out
1 mm ORTEC 142PC keithley picoammeter 6485
Fig. 3. Schematic view of the experimental setup used to investigate the basic performance of a hole-type MPGD with (a) a single GP, and (b) a double GP, made of PEG3C.
material for the production of a bialkali photocathode in a gaseous PMT. At first, we fabricated a GP using PEG3C with a thickness of 150 μm, having an effective diameter of 20 mm and holes
with a diameter and a pitch of 100 μm and 360 μm, respectively. A performance test was carried out using an X-ray beam. The detector was operated with the gas mixtures Ne (90%) + CF4 (10%) and Ne (90%) + i-C4H10 (10%) at a pressure of 1 atm. We successfully obtained an effective gain of 5 103 and an energy resolution of 17% for 6 keV X-rays using a single GP, whereas we achieved an effective gain of up to 6 104 in a tandem operation using a double GP. The relative gain and the energy resolution remained almost constant for X-ray beam rates per unit area in the range from 1.1 104 to 1.3 106 counts/s/mm2. We are currently developing a gaseous PMT with a bialkali photocathode using a GP made of PEG3C.
276
F. Tokanai et al. / Nuclear Instruments and Methods in Physics Research A 732 (2013) 273–276
Constant Mean Sigma
peg3c.006
60000
2500
50000
2000
Counts
Counts
70000
40000 30000
2651 ± 8.6 284.4 ± 0.1 24.62 ± 0.06
1500 1000
20000 500
10000
0
0
0
50
100
150
200
250
300
350
400
450
500
0
50
100
150
200
250
300
350
400
450
500
ADC channel
ADC channel Fig. 5. Pulse height distribution for a hole-type MPGD with a GP made of PEG3C for an effective gain of 3000. The MPGD is filled with Ne (90%) + CF4 (10%) at 1 atm. The energy resolution is 17% (FWHM) for 6 keV X-rays.
Fig. 8. Pulse height distribution for the hole-type MPGD with a double GP for 6 keV X-rays at an effective gain of 10,000. The MPGD is filled with Ne (90%) + CF4 (10%) at 1 atm. The applied voltages for Vcathode, VGP1_in, VGP2_out, VGP2_in and VGP2_out are 1050 V, 1000 V, 600 V, 500 V and 400 V, respectively. The energy resolution is 20% (FWHM) for 6 keV X-rays.
30 1.4
Acknowledgments
Relative gain
Energy resolution
25
1 0.8
20
0.6 0.4
15
0.2 0
Energy resolution (%)
Relative gain 1.2
10 0
2000
4000
6000
8000
10000
12000
Beam intensity (counts/s) Fig. 6. Stabilities of gain and energy resolution of the hole-type MPGD with a GP made of PEG3C for the gas mixture Ne (90%) + CF4 (10%) at 1 atm. The beam intensity is defined as the count rate obtained by the MPGD. The relative gains are normalized by the peak ADC channel obtained at a beam intensity of 87 counts=s.
105 Double Ne(90%)+CF4(10%)
Gain
104
103
102 2nd Ne(90%)+CF4(10%) 1st Ne(90%)+CF4(10%)
10
1 200
250
300
350
400
450
500
550
600
Δ VGP [V] Fig. 7. Gain of the double GP made of PEG3C, for the Ne (90%) + CF4 (10%) gas mixture at 1 atm as a function of the voltage between the electrodes of each GP obtained with 6 keV X-rays.
This work was supported by a JSPS Grant-in-Aid (256100482) and by a JST advanced characterization technology and instrument development project. References [1] A. Oed, Nuclear Instruments and Methods in Physics Research Section A 263 (1988) 351. [2] H. Sakurai, et al., Nuclear Instruments and Methods in Physics Research Section A 374 (1996) 341. [3] Y. Giomataris, Nuclear Instruments and Methods in Physics Research Section A 376 (1996) 84. [4] F. Sauli, Nuclear Instruments and Methods in Physics Research Section A 386 (1997) 531. [5] F. Sauli, Nuclear Instruments and Methods in Physics Research Section A 623 (2010) 29. [6] F. Tokanai, et al., IEEE Transactions on Nuclear Science NS-52 (2005) 1698. [7] F. Tokanai, et al., Nuclear Instruments and Methods in Physics Research Section A 628 (2011) 190. [8] J.F. Clergeau, et al., Nuclear Instruments and Methods in Physics Research Section A 471 (2001) 60. [9] F. Tokanai, et al., Nuclear Instruments and Methods in Physics Research Section A 610 (2009) 104. [10] H. Takahashi, et al., Nuclear Instruments and Methods in Physics Research A 724 (2013) 1. [11] F. Tokanai, et al., Nuclear Instruments and Methods in Physics Research Section A 581 (2007) 236. [12] R. Bellazzini, et al., Nuclear Instruments and Methods in Physics Research Section A 419 (1998) 429. [13] S. Bachmann, et al., Nuclear Instruments and Methods in Physics Research Section A 438 (1999) 376.
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research A journal homepage: www.elsevier.com/locate/nima
Novel glass ceramic-type micropattern gas detector with PEG3C Fuyuki Tokanai a,n, Toru Moriya a, Mirei Takeyama a, Hirohisa Sakurai a, Shuichi Gunji a, Takashi Fushie b, Hajime Kikuchi c, Takayuki Sumiyoshi d, Hirioyuki Sugiyama e, Teruyuki Okada e, Noboru Ohishi e, Syunji Kishimoto f, Hideki Hamagaki g a
Department of Physics, Yamagata University, Yamagata 990-8560, Japan PEG Project Blanks Division, HOYA CORPORATION, Tochigi 321-4292, Japan c HOYA CORPORATION, Yamanashi 408-8550, Japan d Graduate School of the Faculty of Science and Engineering, Tokyo Metropolitan University, Tokyo 192-0397, Japan e Electron Tube Division, Hamamatsu Photonics K.K., Shizuoka 438-0193, Japan f Institute of Material Structure Science, KEK, Tsukuba 305-0801, Japan g Center for Nuclear Study, Graduate School of Science, the University of Tokyo, Saitama 351-0198, Japan b
art ic l e i nf o
a b s t r a c t
Available online 9 August 2013
A new glass plate (GP) has been developed for a hole-type micropattern gas detector (MPGD). The material of the GP is a crystallized photosensitive etching glass (PEG3C) made by Hoya Corporation. A basic performance test of the hole-type MPGD was carried out using an X-ray beam with Ne-based gas mixtures at 1 atm. Gains of up to 5 103 and 6 104 were obtained using a single and a double GP, respectively. An energy resolution of 17% was obtained for 6 keV X-rays with a single GP. It was also shown that there is little charging-up effect in the GP. In this paper, we report the characteristics of the new hole-type MPGD with a GP made of PEG3C. & 2013 Elsevier B.V. All rights reserved.
Keywords: Gaseous PMT Glass ceramic plate Micropattern gas detector
1. Introduction Since the invention of the microstrip gas detector by Oed [1], various types of gaseous detectors with high granularity, referred to as micropattern gas detectors (MPGDs) [2–4], have emerged and been widely used in various fields. At present, one of the most popular and useful MPGDs is the hole-type MPGD, as typified by the gas electron multiplier (GEM) [4]. A hole-type MPGD typically consists of a thin insulator sheet (0.05–2 mm thick) with a large number of small holes (0.01–1 mm diameter). The main applications and the development of the GEM have been reviewed in the literature [5]. A glass capillary is another popular hole-type MPGD. The insulator is a lead glass or a Pyrex glass, and the holes are made by employing the standard manufacturing process for a microchannel plate (MCP) [2,6] or using a microblasting technique [7]. The glass material of the MPGD is very promising for the development of a neutron detector and of a gaseous photomultiplier tube (PMT) for visible light. 3He gas is used as the neutron converter in the gas detector. However, the high cost of the 3He gas makes it impractical to flush 3He gas through the detector during a long operation. 3He is suitable for use in a sealed neutron detector, because the low outgassing from the glass renders possible for the detector to operate with a good long-term stability [8]. n
Corresponding author. Tel.: +81 236284554. E-mail address: [email protected] (F. Tokanai)
0168-9002/$ - see front matter & 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.nima.2013.08.001
In the case of a gaseous PMT with a bialkali photocathode that is sensitive to visible light, attention must be paid to the high chemical activity of the bialkali metal. By investigating the process of production for a bialkali photocathode in the gaseous PMT, we found that a glass is a more suitable material for the hole-type MPGD than the material of Kapton used in GEMs [9]. Recently, Takahashi and co-workers at the University of Tokyo have generated new interest in a glass GEM with a photosensitive etching glass (PEG) developed by Hoya Corporation (Tokyo, Japan) [10]. Following the successful operation of their glass GEM, we have developed another hole-type MPGD using a new glass ceramic plate, made of a crystallized photosensitive etching glass (PEG3C). In this paper, we describe the characteristics of the novel hole-type MPGD with a PEG3C glass plate. 2. PEG3C as a new material for MPGDs Photosensitive glass is a special glass that allows to form microstructures in the glass using a standard photolithographic method. The glass can be utilized for glass circuit boards used in ink-jet printer heads, in micro-electro-mechanical systems (MEMSs), and in flatpanel displays. Here, we use the crystallized photosensitive etching glass PEG3C developed by Hoya Corporation as a new material for MPGDs. Fig. 1 shows the standard manufacturing process of the hole-type MPGD with a glass plate (GP) made of PEG3C. A
274
F. Tokanai et al. / Nuclear Instruments and Methods in Physics Research A 732 (2013) 273–276
photosensitive glass substrate is prepared. It is then exposed to ultraviolet (UV) light through a photomask. When the glass is heated to about 600 1C in an oven, the UV-exposed region is crystallized. After forming the exposed crystallized part, a diluted hydrofluoric acid is sprayed onto the front and rear surfaces to form through holes. Then the entire substrate with the formed through holes is again irradiated with UV light. The substrate is then heated to 1100 1C to crystallize the glass. Finally, both sides of the glass are metallized with Cu and Cr of 1 μm thickness to form the electrodes of the MPGD. The GPs made of PEG3C are shown in Fig. 2. Fig. 2(a) shows the First Prototype GP with a thickness of 150 μm and an effective diameter of 20 mm. A GP with a large effective area, a square with 100 mm side length, is shown in Fig. 2(b). The First Prototype GP has holes with a diameter of 100 μm and a pitch between the holes of 360 μm (Fig. 2(c)). Fig. 2(d) shows part of a GP with fine holes of 50 μm diameter and 70 μm pitch produced with the current manufacturing process.
3. Basic performance of the GP made of PEG3C In the following performance test, we studied the First Prototype GP made of 150 μm thick PEG3C with an effective diameter of 20 mm, and with holes having a diameter and a pitch of 100 μm and 360 μm, respectively.
1. Glass substrate
2. UV exposure
3.1. Single operation of the hole-type MPGD Fig. 3(a) shows the experimental setup used to investigate the basic performance of the hole-type MPGD with the GP made of PEG3C. The gas gain and the energy resolution were estimated for Ne-based gas mixtures at 1 atm using the X-ray beam at the beamline BL-14A of the Photon Factory in the High Energy Accelerator Research Organization (KEK-PF). The energy of the incident X-ray beam was fixed at 6 keV using a Si double-crystal monochromator. The incident X-rays were defined using a collimator of 0.1 mm diameter. The flux was controlled by adjusting the thickness of the Cu foils installed behind the collimator. The absorption region for the X-rays (drift region) is 5 mm deep between the mesh window and the top of the GP. The induction region between the bottom of the GP and the anode plate has a thickness of 2 mm. The electric fields in the drift and induction regions are set to be 100 V/cm and 1000 V/cm, respectively. Fig. 4 shows the effective gains for the gas mixtures Ne (90%) + CF4 (10%) and Ne (90%) + i-C4H10 (10%) at 1 atm as a function of the voltage across the GP electrodes. The gain values were obtained by measuring the amplitude of the charge output from the anode plate using a digital oscilloscope. Gains of up to 5 103 were safely achieved using a single GP for both gas mixtures. The typical pulse height spectrum in the case of using 6 keV X-rays is shown in Fig. 5 for a gas gain of 3000. The energy resolution is 17%, which is equal to the value obtained using a hole-type MPGD with a glass capillary plate [11]. Fig. 6 shows the dependencies of the gas gain and energy resolution of the MPGD on the X-ray beam intensity. The beam intensity is in the range from 87 to 9962 counts/s, which corresponds to a beam rate per unit area from 1.1 104 to 1.3 106 counts/s/mm2, derived by dividing the beam intensity by the area of the beam collimator with a diameter of 0.1 mm. The relative gains are normalized by the peak ADC channel obtained at a beam rate of 87 counts=s. The relative gain decreases by 5% and the energy resolution deteriorates by 0.6% when the beam intensity is increased to 9962 counts/s. These results show that the charging-up effect of the MPGD is negligible at a beam rate per unit area of 1.3 106 counts/s/mm2. 3.2. Tandem operation of the hole-type MPGD
3. Crystal formation
4. Via etching
5. UV exposure
6. Crystal formation
7. Metalization (Cu / Cr electrode) Fig. 1. Manufacturing process of a hole-type MPGD with a glass plate made of crystallized photosensitive etching glass (PEG3C) developed by Hoya Corporation.
A schematic view of the tandem operation with a double GP is shown in Fig. 3(b). The absorption region for the X-rays (drift region) is again 5 mm deep. The induction region, defined between the upper GP and the lower GP, has a thickness of 2 mm. The transfer region between the bottom of the lower GP and the anode plate is 1 mm thick. The same applied voltage was set for both GPs ðΔV GP Þ throughout the entire measurements. The effective gain was measured by the current mode using an X-ray beam from an X-ray generator, similarly to previous studies [12,13]. Fig. 7 shows the effective gain of the double GP for the Ne (90%) + CF4 (10%) gas mixture at 1 atm as a function of the voltage applied between the electrodes of each GP. The gain of each single GP is also plotted in the figure for comparison. We could achieve a gain of up to 6 104 for the selected gas mixture. The pulse height spectrum in the case of using 6 keV X-rays is shown in Fig. 8 for a gas gain of 10,000. The energy resolution is 20%, which is slightly degraded compared with that obtained using a single GP.
4. Conclusion We reported a new hole-type MPGD with a glass plate (GP) made of a crystallized photosensitive etching glass (PEG3C) developed by Hoya Corporation. PEG3C is expected to be a suitable
F. Tokanai et al. / Nuclear Instruments and Methods in Physics Research A 732 (2013) 273–276
275
Fig. 2. Photographs of GPs made of PEG3C: (a) First Prototype GP with a thickness of 150 μm and an effective diameter of 20 mm; (b) large GP with an effective area of 100 mm 100 mm; (c) scanning electron microscope (SEM) image of the First Prototype GP with holes having a diameter and a pitch of 100 μm and 360 μm, respectively; (d) SEM image of part of a fine-pitch GP with holes having a diameter and a pitch of 50 μm and 70 μm, respectively.
6 keV X-ray
Ne(90%)+i-C4H10(10%)
104
Vcathode
Mesh
Ne(90%)+CF4(10%)
5 mm VGP1_out
2 mm Anode plane
ORTEC 142PC
103
6 keV X-ray Mesh
Vcathode 5 mm VGP1_in
PEG3C_1
VGP1_out
2 mm
460
480
500
520 540 Δ VGP [V]
560
580
600
Fig. 4. Gain of the GPs made of PEG3C, for the gas mixtures Ne (90%) + CF4 (10%) and Ne (90%) + i-C4H10 (10%) at 1 atm as a function of the voltage across the GP electrodes obtained with 6 keV X-rays.
VGP2_in
PEG3C_2 Anode plane
Gain
VGP1_in
PEG3C
VGP2_out
1 mm ORTEC 142PC keithley picoammeter 6485
Fig. 3. Schematic view of the experimental setup used to investigate the basic performance of a hole-type MPGD with (a) a single GP, and (b) a double GP, made of PEG3C.
material for the production of a bialkali photocathode in a gaseous PMT. At first, we fabricated a GP using PEG3C with a thickness of 150 μm, having an effective diameter of 20 mm and holes
with a diameter and a pitch of 100 μm and 360 μm, respectively. A performance test was carried out using an X-ray beam. The detector was operated with the gas mixtures Ne (90%) + CF4 (10%) and Ne (90%) + i-C4H10 (10%) at a pressure of 1 atm. We successfully obtained an effective gain of 5 103 and an energy resolution of 17% for 6 keV X-rays using a single GP, whereas we achieved an effective gain of up to 6 104 in a tandem operation using a double GP. The relative gain and the energy resolution remained almost constant for X-ray beam rates per unit area in the range from 1.1 104 to 1.3 106 counts/s/mm2. We are currently developing a gaseous PMT with a bialkali photocathode using a GP made of PEG3C.
276
F. Tokanai et al. / Nuclear Instruments and Methods in Physics Research A 732 (2013) 273–276
Constant Mean Sigma
peg3c.006
60000
2500
50000
2000
Counts
Counts
70000
40000 30000
2651 ± 8.6 284.4 ± 0.1 24.62 ± 0.06
1500 1000
20000 500
10000
0
0
0
50
100
150
200
250
300
350
400
450
500
0
50
100
150
200
250
300
350
400
450
500
ADC channel
ADC channel Fig. 5. Pulse height distribution for a hole-type MPGD with a GP made of PEG3C for an effective gain of 3000. The MPGD is filled with Ne (90%) + CF4 (10%) at 1 atm. The energy resolution is 17% (FWHM) for 6 keV X-rays.
Fig. 8. Pulse height distribution for the hole-type MPGD with a double GP for 6 keV X-rays at an effective gain of 10,000. The MPGD is filled with Ne (90%) + CF4 (10%) at 1 atm. The applied voltages for Vcathode, VGP1_in, VGP2_out, VGP2_in and VGP2_out are 1050 V, 1000 V, 600 V, 500 V and 400 V, respectively. The energy resolution is 20% (FWHM) for 6 keV X-rays.
30 1.4
Acknowledgments
Relative gain
Energy resolution
25
1 0.8
20
0.6 0.4
15
0.2 0
Energy resolution (%)
Relative gain 1.2
10 0
2000
4000
6000
8000
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Beam intensity (counts/s) Fig. 6. Stabilities of gain and energy resolution of the hole-type MPGD with a GP made of PEG3C for the gas mixture Ne (90%) + CF4 (10%) at 1 atm. The beam intensity is defined as the count rate obtained by the MPGD. The relative gains are normalized by the peak ADC channel obtained at a beam intensity of 87 counts=s.
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Δ VGP [V] Fig. 7. Gain of the double GP made of PEG3C, for the Ne (90%) + CF4 (10%) gas mixture at 1 atm as a function of the voltage between the electrodes of each GP obtained with 6 keV X-rays.
This work was supported by a JSPS Grant-in-Aid (256100482) and by a JST advanced characterization technology and instrument development project. References [1] A. Oed, Nuclear Instruments and Methods in Physics Research Section A 263 (1988) 351. [2] H. Sakurai, et al., Nuclear Instruments and Methods in Physics Research Section A 374 (1996) 341. [3] Y. Giomataris, Nuclear Instruments and Methods in Physics Research Section A 376 (1996) 84. [4] F. Sauli, Nuclear Instruments and Methods in Physics Research Section A 386 (1997) 531. [5] F. Sauli, Nuclear Instruments and Methods in Physics Research Section A 623 (2010) 29. [6] F. Tokanai, et al., IEEE Transactions on Nuclear Science NS-52 (2005) 1698. [7] F. Tokanai, et al., Nuclear Instruments and Methods in Physics Research Section A 628 (2011) 190. [8] J.F. Clergeau, et al., Nuclear Instruments and Methods in Physics Research Section A 471 (2001) 60. [9] F. Tokanai, et al., Nuclear Instruments and Methods in Physics Research Section A 610 (2009) 104. [10] H. Takahashi, et al., Nuclear Instruments and Methods in Physics Research A 724 (2013) 1. [11] F. Tokanai, et al., Nuclear Instruments and Methods in Physics Research Section A 581 (2007) 236. [12] R. Bellazzini, et al., Nuclear Instruments and Methods in Physics Research Section A 419 (1998) 429. [13] S. Bachmann, et al., Nuclear Instruments and Methods in Physics Research Section A 438 (1999) 376.