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Load capacity and recovery behaviour of ALD-coated MCP-PMTs
Nuclear Inst. and Methods in Physics Research, A 949 (2020) 162854
Contents lists available at ScienceDirect
Nuclear Inst. and Methods in Physics Research, A journal homepage: www.elsevier.com/locate/nima
Technical notes
Load capacity and recovery behaviour of ALD-coated MCP-PMTs Yu. Melikyan a ,∗, T. Sýkora b , T. Komárek c , L. Nožka c , D. Serebryakov a , V. Urbášek c a
Institute for Nuclear Research of the Russian Academy of Sciences, V-312, 60-letiya Oktyabrya prospect 7a, Moscow, 117312, Russia Charles University, Faculty of Mathematics and Physics, Institute of Particle and Nuclear Physics, V Holešovičkách 2, CZ — 18000 Praha 8, Czech Republic Palacky University, Faculty of Science, RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of the Academy of Sciences of the Czech Republic, 17. listopadu 12, 771 46 Olomouc, Czech Republic b c
ARTICLE
INFO
Keywords: MCP-PMT Atomic Layer Deposition (ALD) PMT linearity Recovery time
ABSTRACT We report the saturation and recovery properties of ALD-coated MCP-PMTs produced by Hamamatsu Photonics K.K. and Photek Ltd. compared to a non-ALD device produced by Photonis, Inc. Similar study has been done previously for ALD-coated Photonis MCP-PMTs. The obtained results confirm that ALD-coated MCP-PMTs produced by any of these manufacturers feature an unexpectedly long time needed for the gain recovery once the saturation was reached (from few minutes up to more than an hour). Despite the saturation level in terms of the average anode current for such devices may reach 0.4 μA/cm2 their use in high load accelerator-based experiments requires additional precaution to avoid driving an MCP-PMT to a saturated mode even for a short time before the start of any data taking period.
Application of the Atomic Layer Deposition (ALD) technique to the microchannel plates (MCP) production for the use in MCP-PMTs increases the devices’ lifetime from 0.1. . . 1 C/cm2 [1,2] up to ∼20 C/cm2 [2,3]. This paves the way for the MCP-PMTs use in particle detectors for a number of high-energy physics experiments, such as timing system of the ATLAS Forward Proton detector [4], TORCH detector for the LHCb upgrade [5], PANDA barrel and endcap DIRC detectors [3], TOP counter for the BELLE-II experiment [2] and DIRC detector for the future Electron Ion Collider experiment [6]. Apart from the excellent timing below 100 ps at single photon level, high spatial segmentation (1. . . 7 mm linear anode dimensions) and lifetime up to 5 C/cm2 , some of these applications require the MCP-PMTs to have a linear response for the average anode current (AAC) up to 200 nA/cm2 or even more. Recently, an unexpectedly low load capacity in terms of the average anode current (∼10 nA/cm2 ) has been observed for two samples of ALD-coated MCP-PMTs produced by Photonis, Inc. [7]. Moreover, the same devices featured an extremely long recovery time (≳1 h). Since their non-ALD counterparts featured a good performance (∼0.8 μA/cm2 load capacity and immediate gain recovery), the observed problems were associated with the ALD coating of the MCP stack. In this study, ALD-coated MCP-PMTs produced by two other manufacturers (Hamamatsu Photonics K.K. and Photek, Ltd.) have been tested in a setup similar to the one used in [7]. A non-ALD coated
MCP-PMT has also been tested in the same setup and then served as a reference. All relevant parameters of the tested devices are listed in Table 1. Each MCP-PMT was illuminated by short (<50 ps FWHM) pulses of 440 nm light reflected from a diffuse mirror for a uniform illumination of the whole sensitive area of the device. Only a single readout channel was monitored from each device by 1 GHz LeCroy WR8104 oscilloscope. Each device was equipped with a voltage divider with the default resistors ratio1 recommended by the manufacturer [8–10]. To determine the exact load capacity in terms of AAC, the illumination rate for each device was increased step-by-step from a very low level (10. . . 20 Hz) to a level high enough to observe the gain decrease due to a lack of the MCP recovery current (0.3. . . 3 MHz). The results are presented in Fig. 1. For the average anode current above 0.1 μA/cm2 , device #2 feature ‘‘superlinearity’’, which was already observed for similar devices of the same manufacturer [11]. Its reasons are beyond the scope of this article and thoroughly discussed in [11]. From the practical point of view, we specify the device load capacity as the AAC level causing 10% variation in the PMT gain (either positive or negative). As a result, the following limits have been observed: 0.6 μA/cm2 , 0.2 μA/cm2 and 0.5 μA/cm2 for devices #1, #2 and #3 respectively. These values are higher by at least an order of magnitude than those observed previously for the ALD-coated Photonis MCP-PMTs tested in similar conditions [7].
∗ Corresponding author. E-mail address: [email protected] (Yu. Melikyan). 1 Device #1: Photocathode – MCP1 in – MCP1 out – MCP2 in – MCP2 out – Ground: 0.22M : 1.1M : 1.1M : 1.1M : 0.66M; Device #2: Photocathode – MCP in – MCP out – Ground: 1M : 19.6M : 5.6M; Device #3: Photocathode – MCP in – MCP out – Ground: 0.5M : 5M : 0.5M.
https://doi.org/10.1016/j.nima.2019.162854 Received 8 June 2019; Received in revised form 19 September 2019; Accepted 23 September 2019 Available online 25 September 2019 0168-9002/© 2019 Elsevier B.V. All rights reserved.
Yu. Melikyan, T. Sýkora, T. Komárek et al.
Nuclear Inst. and Methods in Physics Research, A 949 (2020) 162854
Table 1 Parameters of the tested MCP-PMTs. Device #
1
2
3
Type Manufacturer Pore diameter ALD-coating of the MCPs Sensitive area Resistance of the MCP stack Total bias voltage Unsaturated electron gain Light intensity (detected p.e./pulse/cm2 ) MCP strip current density Sensitive area of an individual readout channel Serial number
R10754-07-M16 Hamamatsu 10 μm Yes 23 × 23 mm2 105 MΩ 1600 V 5*104 90 1.5 uA/cm2 5.3 × 5.3 mm2 KT0714
PMT253 Photek 15 μm Yes 53 × 53 mm2 14.9 MΩ 3000 V 2*105 5*102 4.1 uA/cm2 6.6 × 6.6 mm2 A1171005
XP85002/FIT-Q Photonis 25 μm No 53 × 53 mm2 14 MΩ 1285 V 1.5*104 2*103 2.6 uA/cm2 26.5 × 26.5 mm2 9002140
Fig. 1. Gain variation with the increase of the average anode current of each device caused by a proportional increase of the illumination rate.
Table 2 MCP-PMT recovery characteristics. Device #
1
2
3
Phase 1 duration Phase 2 duration Initial voltage across the MCP stack (UMCP ) UMCP during phase 2
185 s 50 min 834 V
80 s 32 min 1700 V
20 s 13 min 1016 V
834 ± 0.5 V
1691 ± 1 V
1016 ± 0.5 V
To check the recovery behaviour of the devices under study, the signal amplitude has constantly been measured and logged at 200 Hz readout rate limit once the saturation was reached. The results are presented in Fig. 2. After a short period of operation at the illumination rate high enough to cause saturation (≥0.3 MHz, phase 1 in Fig. 2), the illumination rate has been immediately switched over to a knowingly unsaturated mode (≤100 Hz, phase 2 in Fig. 2). The duration of each device operation in both phases is listed in Table 2 along with the voltage values across the MCP stack in the beginning of phase 1 and during the whole phase 2.
Fig. 2. Relative signal value of the tested MCP-PMTs normalized to that of the reference PMT versus integrated number of counts (digitized pulse waveforms).
• device #2 gain recovered to 95% of its original value already in 10 min. The 5% drop in gain observed is correlated to a minor decrease in UMCP , which is likely caused by the MCP heat up; • device #3 gain recovered to 103% of its original value immediately (within less than a period of the low repetition rate). The 3% overshoot in gain is not correlated to any change in UMCP . The origin of such minor discrepancy remains unclear, though may be speculated to be related to some localized heat up effects inside pores.
As a result, the following recovery behaviour was observed for each MCP-PMT: • device #1 gain recovered only to 65% of its original value after 50 min of operation in the unsaturated mode, while the voltage value across the MCP stack (UMCP ) recovered to the initial value already within a second. UMCP is calculated from the measured bias current and known voltage divider resistance values; 2
Yu. Melikyan, T. Sýkora, T. Komárek et al.
Nuclear Inst. and Methods in Physics Research, A 949 (2020) 162854
Conclusion
T. Sýkora gratefully acknowledges the support from the project of MSMT 224 of Czech Republic (LM 2015058). T. Komárek, L. Nožka, V. Urbášek wish to thank for the support from the Operational Programme Research Development and Education-European Regional Development Fund, project no. CZ.02.1.01/0.0/0.0/ 16_019/0000754 of the Ministry of Education, Youth and Sports of the Czech Republic and of Palacky University, Czech Republic IGA_PrF_2019_008.
Both tested ALD-coated MCP-PMTs manufactured by Hamamatsu Photonics K.K. and Photek Ltd. feature an atypical behaviour once their saturation is reached: gain recovery takes more than a few minutes instead of a few milliseconds typically expected for MCP-PMTs. ALD-coated devices manufactured by Photonis Inc. feature a similar problem, reported earlier [7]. The MCP-PMT without the ALD coating behaves predictably with an immediate gain recovery to the initial value. It strengthens the assumption that such a problem is caused by the ALD coating, rather than by other internal properties of the tested devices. If this assumption is true, it complicates the use of such devices in accelerator-based experiments and other applications in which an unpredicted increase of the light intensity is possible both before and during any data taking.
References [1] A. Britting, et al., Lifetime-issues of MCP-pmts, JINST 6 (2011) C10001. [2] K. Matsuoka, et al., Extension of the MCP-pmt lifetime, NIM A 876 (2017) 93–95. [3] A. Lehmann, et al., Tremendously increased lifetime of MCP-pmts, NIM A 845 (2017) 570–574. [4] ATLAS collaboration, ATLAS Forward Proton Phase-I upgrade Technical design report.CERN-LHCC-2015-009. [5] N. Harnew, et al., Status of the TORCH time-of-flight detector, JINST 12 (2017) C11026. [6] G. Kalicy, et al., High-performance DIRC detector for the future electron ion collider experiment, JINST 13 (2018) C04018. [7] E.V. Antamanova, et al., Anode current saturation of ALD-coated planacon® MCP-pmts, JINST 13 (2018) T09001. [8] K.K. Hamamatsu Photonics, Hamamatsu R10754-07-M16 datasheet, 03.2018. [9] Photek Ltd. PMT253 datasheet, 11.04.2019. [10] Photonis, Inc. Planacon XP85002/FIT-Q datasheet, 04.2018. [11] R.A. Buckles, et al., Superlinearity, saturation, and the PMT—Tailoring and calibration methodology for prompt radiation detectors, Rev. Sci. Instrum. 89 (2018) http://dx.doi.org/10.1063/1.5039440.
Acknowledgements We would like to thank our colleagues from Belle II experiment, Profs. K. Matsuoka and K. Inami (Nagoya Univ.), and Tom Conneely, James Milnes and Paul Hink from Photek Inc., as well as Photek Ltd. itself, for their help. We are grateful to M. Milovanovic (AFP, DESY) and Prof. A. Brandt (UTA) for their suggestions and support.
3
Contents lists available at ScienceDirect
Nuclear Inst. and Methods in Physics Research, A journal homepage: www.elsevier.com/locate/nima
Technical notes
Load capacity and recovery behaviour of ALD-coated MCP-PMTs Yu. Melikyan a ,∗, T. Sýkora b , T. Komárek c , L. Nožka c , D. Serebryakov a , V. Urbášek c a
Institute for Nuclear Research of the Russian Academy of Sciences, V-312, 60-letiya Oktyabrya prospect 7a, Moscow, 117312, Russia Charles University, Faculty of Mathematics and Physics, Institute of Particle and Nuclear Physics, V Holešovičkách 2, CZ — 18000 Praha 8, Czech Republic Palacky University, Faculty of Science, RCPTM, Joint Laboratory of Optics of Palacký University and Institute of Physics of the Academy of Sciences of the Czech Republic, 17. listopadu 12, 771 46 Olomouc, Czech Republic b c
ARTICLE
INFO
Keywords: MCP-PMT Atomic Layer Deposition (ALD) PMT linearity Recovery time
ABSTRACT We report the saturation and recovery properties of ALD-coated MCP-PMTs produced by Hamamatsu Photonics K.K. and Photek Ltd. compared to a non-ALD device produced by Photonis, Inc. Similar study has been done previously for ALD-coated Photonis MCP-PMTs. The obtained results confirm that ALD-coated MCP-PMTs produced by any of these manufacturers feature an unexpectedly long time needed for the gain recovery once the saturation was reached (from few minutes up to more than an hour). Despite the saturation level in terms of the average anode current for such devices may reach 0.4 μA/cm2 their use in high load accelerator-based experiments requires additional precaution to avoid driving an MCP-PMT to a saturated mode even for a short time before the start of any data taking period.
Application of the Atomic Layer Deposition (ALD) technique to the microchannel plates (MCP) production for the use in MCP-PMTs increases the devices’ lifetime from 0.1. . . 1 C/cm2 [1,2] up to ∼20 C/cm2 [2,3]. This paves the way for the MCP-PMTs use in particle detectors for a number of high-energy physics experiments, such as timing system of the ATLAS Forward Proton detector [4], TORCH detector for the LHCb upgrade [5], PANDA barrel and endcap DIRC detectors [3], TOP counter for the BELLE-II experiment [2] and DIRC detector for the future Electron Ion Collider experiment [6]. Apart from the excellent timing below 100 ps at single photon level, high spatial segmentation (1. . . 7 mm linear anode dimensions) and lifetime up to 5 C/cm2 , some of these applications require the MCP-PMTs to have a linear response for the average anode current (AAC) up to 200 nA/cm2 or even more. Recently, an unexpectedly low load capacity in terms of the average anode current (∼10 nA/cm2 ) has been observed for two samples of ALD-coated MCP-PMTs produced by Photonis, Inc. [7]. Moreover, the same devices featured an extremely long recovery time (≳1 h). Since their non-ALD counterparts featured a good performance (∼0.8 μA/cm2 load capacity and immediate gain recovery), the observed problems were associated with the ALD coating of the MCP stack. In this study, ALD-coated MCP-PMTs produced by two other manufacturers (Hamamatsu Photonics K.K. and Photek, Ltd.) have been tested in a setup similar to the one used in [7]. A non-ALD coated
MCP-PMT has also been tested in the same setup and then served as a reference. All relevant parameters of the tested devices are listed in Table 1. Each MCP-PMT was illuminated by short (<50 ps FWHM) pulses of 440 nm light reflected from a diffuse mirror for a uniform illumination of the whole sensitive area of the device. Only a single readout channel was monitored from each device by 1 GHz LeCroy WR8104 oscilloscope. Each device was equipped with a voltage divider with the default resistors ratio1 recommended by the manufacturer [8–10]. To determine the exact load capacity in terms of AAC, the illumination rate for each device was increased step-by-step from a very low level (10. . . 20 Hz) to a level high enough to observe the gain decrease due to a lack of the MCP recovery current (0.3. . . 3 MHz). The results are presented in Fig. 1. For the average anode current above 0.1 μA/cm2 , device #2 feature ‘‘superlinearity’’, which was already observed for similar devices of the same manufacturer [11]. Its reasons are beyond the scope of this article and thoroughly discussed in [11]. From the practical point of view, we specify the device load capacity as the AAC level causing 10% variation in the PMT gain (either positive or negative). As a result, the following limits have been observed: 0.6 μA/cm2 , 0.2 μA/cm2 and 0.5 μA/cm2 for devices #1, #2 and #3 respectively. These values are higher by at least an order of magnitude than those observed previously for the ALD-coated Photonis MCP-PMTs tested in similar conditions [7].
∗ Corresponding author. E-mail address: [email protected] (Yu. Melikyan). 1 Device #1: Photocathode – MCP1 in – MCP1 out – MCP2 in – MCP2 out – Ground: 0.22M : 1.1M : 1.1M : 1.1M : 0.66M; Device #2: Photocathode – MCP in – MCP out – Ground: 1M : 19.6M : 5.6M; Device #3: Photocathode – MCP in – MCP out – Ground: 0.5M : 5M : 0.5M.
https://doi.org/10.1016/j.nima.2019.162854 Received 8 June 2019; Received in revised form 19 September 2019; Accepted 23 September 2019 Available online 25 September 2019 0168-9002/© 2019 Elsevier B.V. All rights reserved.
Yu. Melikyan, T. Sýkora, T. Komárek et al.
Nuclear Inst. and Methods in Physics Research, A 949 (2020) 162854
Table 1 Parameters of the tested MCP-PMTs. Device #
1
2
3
Type Manufacturer Pore diameter ALD-coating of the MCPs Sensitive area Resistance of the MCP stack Total bias voltage Unsaturated electron gain Light intensity (detected p.e./pulse/cm2 ) MCP strip current density Sensitive area of an individual readout channel Serial number
R10754-07-M16 Hamamatsu 10 μm Yes 23 × 23 mm2 105 MΩ 1600 V 5*104 90 1.5 uA/cm2 5.3 × 5.3 mm2 KT0714
PMT253 Photek 15 μm Yes 53 × 53 mm2 14.9 MΩ 3000 V 2*105 5*102 4.1 uA/cm2 6.6 × 6.6 mm2 A1171005
XP85002/FIT-Q Photonis 25 μm No 53 × 53 mm2 14 MΩ 1285 V 1.5*104 2*103 2.6 uA/cm2 26.5 × 26.5 mm2 9002140
Fig. 1. Gain variation with the increase of the average anode current of each device caused by a proportional increase of the illumination rate.
Table 2 MCP-PMT recovery characteristics. Device #
1
2
3
Phase 1 duration Phase 2 duration Initial voltage across the MCP stack (UMCP ) UMCP during phase 2
185 s 50 min 834 V
80 s 32 min 1700 V
20 s 13 min 1016 V
834 ± 0.5 V
1691 ± 1 V
1016 ± 0.5 V
To check the recovery behaviour of the devices under study, the signal amplitude has constantly been measured and logged at 200 Hz readout rate limit once the saturation was reached. The results are presented in Fig. 2. After a short period of operation at the illumination rate high enough to cause saturation (≥0.3 MHz, phase 1 in Fig. 2), the illumination rate has been immediately switched over to a knowingly unsaturated mode (≤100 Hz, phase 2 in Fig. 2). The duration of each device operation in both phases is listed in Table 2 along with the voltage values across the MCP stack in the beginning of phase 1 and during the whole phase 2.
Fig. 2. Relative signal value of the tested MCP-PMTs normalized to that of the reference PMT versus integrated number of counts (digitized pulse waveforms).
• device #2 gain recovered to 95% of its original value already in 10 min. The 5% drop in gain observed is correlated to a minor decrease in UMCP , which is likely caused by the MCP heat up; • device #3 gain recovered to 103% of its original value immediately (within less than a period of the low repetition rate). The 3% overshoot in gain is not correlated to any change in UMCP . The origin of such minor discrepancy remains unclear, though may be speculated to be related to some localized heat up effects inside pores.
As a result, the following recovery behaviour was observed for each MCP-PMT: • device #1 gain recovered only to 65% of its original value after 50 min of operation in the unsaturated mode, while the voltage value across the MCP stack (UMCP ) recovered to the initial value already within a second. UMCP is calculated from the measured bias current and known voltage divider resistance values; 2
Yu. Melikyan, T. Sýkora, T. Komárek et al.
Nuclear Inst. and Methods in Physics Research, A 949 (2020) 162854
Conclusion
T. Sýkora gratefully acknowledges the support from the project of MSMT 224 of Czech Republic (LM 2015058). T. Komárek, L. Nožka, V. Urbášek wish to thank for the support from the Operational Programme Research Development and Education-European Regional Development Fund, project no. CZ.02.1.01/0.0/0.0/ 16_019/0000754 of the Ministry of Education, Youth and Sports of the Czech Republic and of Palacky University, Czech Republic IGA_PrF_2019_008.
Both tested ALD-coated MCP-PMTs manufactured by Hamamatsu Photonics K.K. and Photek Ltd. feature an atypical behaviour once their saturation is reached: gain recovery takes more than a few minutes instead of a few milliseconds typically expected for MCP-PMTs. ALD-coated devices manufactured by Photonis Inc. feature a similar problem, reported earlier [7]. The MCP-PMT without the ALD coating behaves predictably with an immediate gain recovery to the initial value. It strengthens the assumption that such a problem is caused by the ALD coating, rather than by other internal properties of the tested devices. If this assumption is true, it complicates the use of such devices in accelerator-based experiments and other applications in which an unpredicted increase of the light intensity is possible both before and during any data taking.
References [1] A. Britting, et al., Lifetime-issues of MCP-pmts, JINST 6 (2011) C10001. [2] K. Matsuoka, et al., Extension of the MCP-pmt lifetime, NIM A 876 (2017) 93–95. [3] A. Lehmann, et al., Tremendously increased lifetime of MCP-pmts, NIM A 845 (2017) 570–574. [4] ATLAS collaboration, ATLAS Forward Proton Phase-I upgrade Technical design report.CERN-LHCC-2015-009. [5] N. Harnew, et al., Status of the TORCH time-of-flight detector, JINST 12 (2017) C11026. [6] G. Kalicy, et al., High-performance DIRC detector for the future electron ion collider experiment, JINST 13 (2018) C04018. [7] E.V. Antamanova, et al., Anode current saturation of ALD-coated planacon® MCP-pmts, JINST 13 (2018) T09001. [8] K.K. Hamamatsu Photonics, Hamamatsu R10754-07-M16 datasheet, 03.2018. [9] Photek Ltd. PMT253 datasheet, 11.04.2019. [10] Photonis, Inc. Planacon XP85002/FIT-Q datasheet, 04.2018. [11] R.A. Buckles, et al., Superlinearity, saturation, and the PMT—Tailoring and calibration methodology for prompt radiation detectors, Rev. Sci. Instrum. 89 (2018) http://dx.doi.org/10.1063/1.5039440.
Acknowledgements We would like to thank our colleagues from Belle II experiment, Profs. K. Matsuoka and K. Inami (Nagoya Univ.), and Tom Conneely, James Milnes and Paul Hink from Photek Inc., as well as Photek Ltd. itself, for their help. We are grateful to M. Milovanovic (AFP, DESY) and Prof. A. Brandt (UTA) for their suggestions and support.
3