ANL MCP Testing: Status and Plans

Transcription

1 University of Chicago ANL MCP Testing: Status and Plans --

2 The IRISS (Infrared International Spacer Station) On Friday, we finished reconfiguring the ISS with a thick quartz top-window, to allow thermal imaging of MCPs under HV. We were successful in bringing the vacuum down to a few torr and pass a small current through a stack consisting of (chem) MCP between two grid spacers. Quartz was not sitting evenly on the ISS surface. In the process of diagnosing the problem, we broke the O-ring. Working on a replacement today and hope to resume testing.

3 The IRISS (Infrared International Spacer Station) Tom s directorial debut We also, set up and experimented with the HEP division IR camera. We needed to experiment with setting the color scale and range In particular, we wanted to know: does enough IR transmit through the quartz window?

4 The IRISS (Infrared International Spacer Station) Here is Andrey s world premier on IR TV

5 The IRISS (Infrared International Spacer Station) Here he is, attempting to conceal his identity behind the quartz window Nice try...

6 The IRISS (Infrared International Spacer Station) It seems that some IR is able to penetrate through the quartz. We experimented a little with the quartz while it was sitting on the ISS. The quartz seems largely opaque with the detector system is at thermal equilibrium (for obvious reasons). However, we are hopeful that as the plates heat up, under HV, they should be visible beneath the window. We hope to get the system down to a proper vacuum today, where we can experiment with imaging it under proper operation. If we can image the plates thermally with sufficient resolution, it will be good to think about next steps. We have three resources available to us: the mm chamber for testing mm MCPs and MCPs cut to mm discs The ISS and the IRISS The demountable How best to use these resources Any material-science resources to help study and diagnose MCPs?

7 mm Testing Program Systematic studies Tubulation Flight of L/D (starting June ) (late summer) One-off studies After Pulsing Pore Saturation I Pore Saturation II (mid-summer) (late summer) (???)

8 mm Testing Program Systematic studies Tubulation Flight of L/D (starting June ) (late summer) Tubulation program is now on schedule. Testing different L/Ds will require: electroding and ALD coating of substrates scheduling around other APS activities One-off studies After Pulsing Pore Saturation I Pore Saturation II (mid-summer) (late summer) (???) After-pulsing study can be performed on MCPs before exposure to Cs/K and can be worked in seamlessly with the tubulation work After discussion with ernhard and Andrey, we felt that pore saturation would make a good, doable project for Thomas. Phase I would involve using a pulsed UV diode. Time permitting, Phase II would involve controlled optical delay of the laser

9 Tubulation Study Our tubulation-based PC study, using the mm chamber was delayed for a variety of reasons: decided to make new parts busted HV supply many other activities going on Fortunately, now we have a largely complete checklist and seem to be onschedule for first testing in mid-june hole. (.) A A trench. (.) A A (.) (.). hole A:.mm straight hole :. mm, countersunk, deep mm deep trench floor detail hole A. (/") material: glass dimensions in mm (in.) sloping down deg..w. Adams

10 Planned Schedule Where We Are All of the vacuum and optical components designed and done Chamber under vacuum and working Glass holder almost finished Necessary parts have been ordered Repairs on the W-IE-NE-R power supply are almost finished Half of our mm sample (aluminum oxide) are done and in our possession Where We re Going Need to finish design for spectator photocathode Have the spectator PC made Waiting on glass holder to be finished repairs to be finished ordered parts to come in Will almost certainly be done by the week of June

11 Planned Schedule Where We Are All of the vacuum and optical components designed and done Chamber under vacuum and working Glass holder almost finished Necessary parts have been ordered Repairs on the W-IE-NE-R power supply are almost finished Half of our mm sample (aluminum oxide) are done and in our possession Where We re Going Need to finish design for spectator photocathode Have the spectator PC made Waiting on glass holder to be finished repairs to be finished ordered parts to come in Will almost certainly be done by the week of June Today (/) June - staging and first tubulation study ~ ~ ~ ~ ~ ~

12 and Demountable Tests - Documenting Our Work RSI Paper A skeleton of the paper exists The data analysis issues are worked out Hope to have a complete rough draft when I m back on June with silver mircrostriplines silk-screed onto a glass plate. The MCPs are separated from each other and from the anode with glass grid-spacers. Five stainless steel electodes contact the top and bottom of the MCPs and the anode, which consists of a thin layer of Aluminum deposited on a quartz window. In the larger testing chamber, square MCPs sit in a glass tray at the bottom of the chamber (shown in Fig??). The laser beam enters through a fused silica vacuum window on the side of the chamber, and is reflected downward onto the stack by an array of mirrors at degrees. Signals and high voltages are connected to feed-throughs on a flange attached to the top of the chamber. The holder for MCPs is a glass tray designed to the same specifications as the glass-body, sealed-tube design developed by University of Chicago and ANL. Free from the constraint of sealing the tube, this setup can also accomodate variable stacks of one or more MCPs and varrious spacings. Glass grid spacers, similar to those in the design for the vacuum tubes, are used to separate the various components of the stack. The anode is contrained to the silver delay-line design. Attached to a fan-out board with SMA connectors, and mounted on breadboard that it shares with the optics. Springy cross-bars apply pressure. LAPPD anode coverage over large areas is achieved using a micro-stripline design []. The position of the impinging photons in the direction parallel to the striplines is measured from the differential time between the signal arrival at the two ends of a stripline. In the perpendicular direction, we determine the hit position by taking a weighted centroid of integrated charge on the stripline and its nearest neighbors. This design is ideal for economical MCPs as the number of readout channels scales with length, rather than area. Trigger signal. UVPD-based calibration. Statistical argument used to identify single-pe operation without needing detailed calibration for the quantum efficiency of our Aluminum photocathode.. Samples Timing and Gain Characteristics of a Complete, Large Area MCP Detector System. Adamsb, A. Elagina, H. Frischa, R. Obaida,, A. Vostrikova, M. Wetsteina a Enrico Fermi Institute, University of Chicago National Laboratory b Argonne Abstract The LAPPD project is...we now have working inch MCPS...Description of anode and its importance...in this paper we present the results of a complete cathode-to-anode detector system using our economical microstripline anode, operated in a high vacuum test chamber. Transit time spread is psec We observe the pulse height distribution for our MCP pair peaked at gains above e. Hit positions in the parallel direction are determined by...we measure a differential time resolution of XX corresponding to YY mm in spatial terms. Position in the perpendicular direction is given by signal centroid. We determine this resolution to be... We also discuss analysis and optimization of the detector. Keywords: microchannel, MCP, time-of-flight, water-cherenkov, neutrinos PACS:..Qk,..Qk,..Hp,..Lg. Introduction The two MCPs...chem, resistances of XX and YY, respectively. Secondary emissive layer consisting of aluminum oxide(?). Early samples, some non-uniformity in the gain profile. Newer plates are much better in this respect. Still sufficient to establish the timing characteristics.. Data Acquisition Microchannel plate photomultiplier tubes (MCP-PMTs) are compact photodetectors [], capable of spatial resolutions down to several microns [], time resolutions measured in psec [,, ] and gains exceeding []. The dark-current noise of MCP-PMT s is dominated by the application-specific photocathode, as the MCP s themselves have noise levels below. counts/cm -sec []. If MCP-PMT s were comparable in price and robustness to dynode-based photomultipliers, they would add a needed capability for high-resolution imaging in time and space for a wide variety of applications such as high energy particle physics, nuclear physics, material science, and medical imaging. The Large Area Picosecond Photodetector (LAPPD) collaboration is developing techniques for making large-format MCP-PMT detector systems using scalable methods and low cost materials, addressing all aspects of the problem, from the photocathode and the gain stage, to the readout electronics and vacuum packaging. A central aspect of the project is a technique known as Atomic Layer Deposition (ALD) [], which enables the fabrication of large-area MCP amplification structures by conformally coating inactive, porous glass substrates [, ]. The technique allows for the independent optimization of the geometric, resistive, and secondary electron emission properties [] of the channel plates. In this paper, we present our first characterization of the timing characteristics for an ALD-functionalized, Large-area michrochannel plate detector system. This detector system achieves the best single-photon transit-time resolution yet demonstrated for the area covered.. Experimental Apparatus and Method Using a laser to characterize photodetectors, only a small region ( mm) is illuminated at a time. To provide more complete characterization of the large area MCP detector, we collect data with the laser directed at many different points on the active area. We use the scanning capabilities and small beam profile of our laser to test the position resolution of our detector. Data are taken for a scan of different laser positions along the central stripline of a three stripline cluster. Differential timing between the arrival of the two signals is used to reconstruct the position parallel to the strip. We use these measurements to determine the propagation speed of signal on the microstriplines. A narrow scan is performed in the transverse direction with respect to the striplines. ecause, at most, only striplines could be read out (as described in Sec??), this scan was restricted to the xx mm region between the outer two striplnes. Several high statistics samples are taken at a single point on the x MCP, to derive the single-pe, and large signal time resolutions. Finally, we collect data for various operational voltages on the MCPs in order to study gain-voltage relationships as well as the timing dependences.. Analysis A pair of x MCPs are tested in a large vacuum chamber. The two plates are assembled in a glass tray, designed to the specifications of our final sealed-tube design. The base of the tray serves as the anode, Now compressable steel ribbon grid-spacer MCP grid-spacer MCP grid-spacer glass anode tray breadboard Figure : Illustration of the MCP test-chamber. SMA and HV feedthroughs turbo pump vacuum region mirror incoming laser beam quartz vacuum window " MCP stack vacuum chamber Figure : A schematic of the MCP test chamber. Figure : Illustration of the MCP test-chamber. at IIT, Chicago Preprint submitted to Elsevier screw cross-bar aluminum coated, quartz window Here we report on our algorithms and analysis techniques. February, Voltage, mv σ =. psec events Noise Signal Events / ( psec) Fourier Transform, d Frequency, GHz gain..... Time, nsec Time, nsec Figure : Pulse height distribution Figure : Frequency spectrum of the MCP signal plus noies (blue) overlaid on the pure noise spectrum (red). Signal dominates over noise onlyup to around MHz. Figure : Transit Time Spread. Results Fourier Transform, d Two different kinds timing measurements are presented in this paper:.) measurements of the absolute arrival time of the signals from each side of the stripline with respect to an external trigger signal, and.) measurements of the arrvial times of the two signals with respect to each other. In either case, filters are used to remove the high-frequency noise and a simple Gaussian is fit to the rising edge of the signal. In the case of the differential timing measurement, the signal and noise spectra are nearly identical, as is the shape of the pulse. For the absoute timing measurements, the fast photodiode used as an external trigger contains different noise and signal spectra from each of the MCP traces. This necessitates different approaches for each of these two cases. A typical example of the pulse shape is shown on Fig.??. There is a fast rising edge (approx. xx psec) and slower falling edge with broad tail. Here we report on the results... Differential Time-Resolution We define the differential time-resolution.. Large Signal ehavior Noise Signal.. Gain Figure shows pulse height distribution. Frequency, GHz.. Review of the Factors that Limit MCP Time Resolution Time resolution of MCP-PDs is determined by characteristics of the readout system, intrinsic jitter in the time response of the MCPs, and on the algorithm used to reconstruct the arrival time. Limitations of the readout system can be parameterized in terms of four key variables: analog bandwidth, sampling rate of the readout electronics, noise-to-signal (N/S), and he rise time of the signals. Intrinsic jitter in the MCP is driven by fluctuations in the first stage of avalanche formation in the MCP and, in particular, the first strike position of the first photoelectron with the MCP pore. The larger the pore diameter, the wider the possible variation of the first-strike position. Figure : Frequency spectrum of the trigger signal plus noies (blue) overlaid on the pure noise spectrum (red). The trigger signal is larger than that of the noise over a much wider frequency range, into the multi-ghz range... Transit Time Spread Figure shows the single photoelectron transit time distribution for one particular position on the MCP detector. We fit this distribution with a Gaussian over a range of +- sigma about the peak. The arrival time resolution is thus determined to be +- (stat) picoseconds. This position was chosen arbitrarily as the reference point for collecting high statistics, single PE data. However, lower statistics data was collected at a variety of other points on the detector. Table?? shows the arival time resolution measured at various points on the detector surface and Fig?? identifies the approximate locations of each of these data sets. These measurements cover a large range of locations in the direction parallel to a single stripline. However, in the transvers direction, we are limited to the range spanned by the four consequative microstriplines accessible to us with vacuum feedthroughs. σ =. psec events As discussed in Sec??, timing characteristics of an MCP detector are expected to improve with signal size. In the limit of N/S, uncertainty on the readout is expected to approach. A good proxy for this uncertainty is the differential time resolution, where intrinsic jitter in the time response of the MCP shows up as a common phase on both sides of the readout, and is subtracted away when we take the difference. Uncertainty in measuring the absolute arrival time of the signal, depends not only on the N/S, but the intrinsic jitter of the MCP response. Even with excellent N/S, singe PE data will be dominated by this jitter, which can only be reduced by increasing the number of photoelectrons. Our data, even when taken with arbitrary light intensity, was dominated by single PE pulses with a small number of pulses with a few PEs. Thus, when we bin our data by N/S, we expect our differential time resolution to improve linearly, approaching for very small N/S, and we expect the absolute time resolution to be dominated by MCP jitter which is estimated to be O() psec for µm Events / ( psec) Figure : An example of our shape-based pulse fit. Pulses are fit with a Gausian over the range from % of the pulse peak, up to and including two points past the signal maximum. Time difference, psec Figure : The differential time resolution for a large-signal sample. the June or July issue relative transit time (seconds) Similarly, the absolute arrival time resolution as a function of N/S was measured. This resolution improved as N/S approached. However, the extrapolated resolution for N/S= was roughly picoseconds. This limit is likely due to intrinsic jitter in the time response of the MCPs, which were operating close to single PE mode. This jitter in arrival time resolution would scale as / N with the number of photoelectrons. Thus, for time-of-flight applications, we expect absolute time resolutions approaching the few picosecond range. Future improvements to MCP design, such as smaller pore sizes, are expected to improve this intrinsic jitter. References Time resolution, psec RSI is done - to be published in CFD Fit CFD & Filter Fit & Filter y =. +.x y =. +.x y =. +.x y =. +.x. Inverse pulse amplitude, V PC Voltage (v) ). Figure : Absolute time resolution plotted as a function of noise/signal for single photoelectron data. In the limits of large signal, the time resolution is estimated to be O() picoseconds due to intrinsic jitter in the MCP time response. In the limits of many photoelectrons, this resolution is expected to scale as (/ NP E Figure : Transit Time Spread as a function of parameters (dummy - MCPs - & Apr, Differential ( ends) resolution, s..... N/S... Figure : Differential time resolution between the two ends of the delay-line anode as a function of noise/signal compared with simulations (in blue). In the limits of large signal this curve approached sub-psec time resolutions. (dummy) [] J. L. Wiza, Microchannel plate detectors, Nucl. Instrum. Methods (). []. O. Siegmund, Paper on resoultion. [] J. Milnes, J. Howorth, Picosecond time response of microchannel plate pmt detectors, Proc. SPIE (). [] M. Akatsu, Y. Enari, K. Hayasaka, T. Hokuue, T. Iijima, K. Inami, K. Itoh, Y. Kawakami, et al, Mcp-pmt timing property for single photons, Nucl. Instrum. Methods A (). [] K. Inami, N. Kishimoto, Y. Enari, M. Nagamine, T. Ohshima, A -ps tof-counter with an mcp-pmt, Nucl. Instrum. Methods A (). []. O. Siegmund, Paper on gain. []. O. Siegmund, Paper on noise. [] S. George, Atomic layer deposition: An overview, Chemical Reviews (). [] S. Jokela, I. Veryovkin, A. Zinovev, J. Elam, Q. Peng,, A. Mane, The characterization of secondary electron emitters for use in large area photo-detectors, Application of Accelerators in Research and Industry AIP Conf. Proc. (). [] N. Sullivan, P. de Rouffignac, D. eaulieu, A. Tremsin, K. Saadatmand, D. Gorelikov, H. Klotzsch, K. Stenton, S. achman, R. Toomey, Novel microchannel plate device fabricated with atomic layer deposition, Proceedings of the Ninth International Conference on Atomic Layer Deposition. [] H. Grabas, R. Obaid, E. Oberla, H. Frisch, J. Genat, R. Northrop, D. McGinnes,. Adams, M. Wetstein, Rf striplineanodes for psec large-area, mcp-based photodetectors, Nucl. Instrum. Methods.. Conclusion A working x Microchannel plate detector system, consisting of ALD-functionalized MCPs and an economical, scalable microstripline anode were tested with a fast, pulsed laser. The detector exhibited a pulse height distribution peaked at gains. Single photoelectron transit time spreads as low as picoseconds and consitently below picosends were observed at a variety of locations on the detector. The differential time resolution between the two ends of the microstripline anode was determined to be picoseconds for single PEs, corresponding to roughly cm spatial resolution in the direction parallel to the strips. In the transverse direction, position was determined using the signal centroid on a cluster of strips. The width of this centroid, corresponding to the transverse position resolution of the detector was mm. These single PE characteristics are excellent for use in applications where diffuse optical light is used to reconstruct charged particle tracks. For collider applications, where time-of-flight is determined by measuring the light of a high energy particle travelling through a radiator, producing O() photoelectrons in a single spot on the detector, the large-signal resolution is much better. We studied the scaling relationship between signal size and time resolution for both the arrival time resolution and the differential resolution. Differential timing depends only on the RF characteristics of the anode and readout, and the signal-tonoise ratio of the pulse. Jitter in the time response of the MCP itself shifts both sides of the signal by a phase, which is subtracted out when we take the difference. Thus, we expect the differential time resolution to approach in the limit where N/S approaches. Measuring the differential time resolution binned by N/S, we observed. picoseconds in the bin with largest signal. Plotting differential time resolution as a function of N/S, we obtain a linear relationship with an intercept of. picoseconds for N/S=. This matches closely with our simulated trendline. The offset of. psec is explainable as a consequence of our finite laser spot size of. mm.

13 and Demountable Tests - Documenting Our Work RSI Paper with silver mircrostriplines silk-screed onto a glass plate. The MCPs are separated from each other and from the anode with glass grid-spacers. Five stainless steel electodes contact the top and bottom of the MCPs and the anode, which consists of a thin layer of Aluminum deposited on a quartz window. In the larger testing chamber, square MCPs sit in a glass tray at the bottom of the chamber (shown in Fig??). The laser beam enters through a fused silica vacuum window on the side of the chamber, and is reflected downward onto the stack by an array of mirrors at degrees. Signals and high voltages are connected to feed-throughs on a flange attached to the top of the chamber. The holder for MCPs is a glass tray designed to the same specifications as the glass-body, sealed-tube design developed by University of Chicago and ANL. Free from the constraint of sealing the tube, this setup can also accomodate variable stacks of one or more MCPs and varrious spacings. Glass grid spacers, similar to those in the design for the vacuum tubes, are used to separate the various components of the stack. The anode is contrained to the silver delay-line design. Attached to a fan-out board with SMA connectors, and mounted on breadboard that it shares with the optics. Springy cross-bars apply pressure. LAPPD anode coverage over large areas is achieved using a micro-stripline design []. The position of the impinging photons in the direction parallel to the striplines is measured from the differential time between the signal arrival at the two ends of a stripline. In the perpendicular direction, we determine the hit position by taking a weighted centroid of integrated charge on the stripline and its nearest neighbors. This design is ideal for economical MCPs as the number of readout channels scales with length, rather than area. Trigger signal. UVPD-based calibration. Statistical argument used to identify single-pe operation without needing detailed calibration for the quantum efficiency of our Aluminum photocathode.. Samples Timing and Gain Characteristics of a Complete, Large Area MCP Detector System. Adamsb, A. Elagina, H. Frischa, R. Obaida,, A. Vostrikova, M. Wetsteina a Enrico Fermi Institute, University of Chicago National Laboratory b Argonne Abstract The LAPPD project is...we now have working inch MCPS...Description of anode and its importance...in this paper we present the results of a complete cathode-to-anode detector system using our economical microstripline anode, operated in a high vacuum test chamber. Transit time spread is psec We observe the pulse height distribution for our MCP pair peaked at gains above e. Hit positions in the parallel direction are determined by...we measure a differential time resolution of XX corresponding to YY mm in spatial terms. Position in the perpendicular direction is given by signal centroid. We determine this resolution to be... We also discuss analysis and optimization of the detector. Keywords: microchannel, MCP, time-of-flight, water-cherenkov, neutrinos PACS:..Qk,..Qk,..Hp,..Lg. Introduction The two MCPs...chem, resistances of XX and YY, respectively. Secondary emissive layer consisting of aluminum oxide(?). Early samples, some non-uniformity in the gain profile. Newer plates are much better in this respect. Still sufficient to establish the timing characteristics.. Data Acquisition Microchannel plate photomultiplier tubes (MCP-PMTs) are compact photodetectors [], capable of spatial resolutions down to several microns [], time resolutions measured in psec [,, ] and gains exceeding []. The dark-current noise of MCP-PMT s is dominated by the application-specific photocathode, as the MCP s themselves have noise levels below. counts/cm -sec []. If MCP-PMT s were comparable in price and robustness to dynode-based photomultipliers, they would add a needed capability for high-resolution imaging in time and space for a wide variety of applications such as high energy particle physics, nuclear physics, material science, and medical imaging. The Large Area Picosecond Photodetector (LAPPD) collaboration is developing techniques for making large-format MCP-PMT detector systems using scalable methods and low cost materials, addressing all aspects of the problem, from the photocathode and the gain stage, to the readout electronics and vacuum packaging. A central aspect of the project is a technique known as Atomic Layer Deposition (ALD) [], which enables the fabrication of large-area MCP amplification structures by conformally coating inactive, porous glass substrates [, ]. The technique allows for the independent optimization of the geometric, resistive, and secondary electron emission properties [] of the channel plates. In this paper, we present our first characterization of the timing characteristics for an ALD-functionalized, Large-area michrochannel plate detector system. This detector system achieves the best single-photon transit-time resolution yet demonstrated for the area covered.. Experimental Apparatus and Method Using a laser to characterize photodetectors, only a small region ( mm) is illuminated at a time. To provide more complete characterization of the large area MCP detector, we collect data with the laser directed at many different points on the active area. We use the scanning capabilities and small beam profile of our laser to test the position resolution of our detector. Data are taken for a scan of different laser positions along the central stripline of a three stripline cluster. Differential timing between the arrival of the two signals is used to reconstruct the position parallel to the strip. We use these measurements to determine the propagation speed of signal on the microstriplines. A narrow scan is performed in the transverse direction with respect to the striplines. ecause, at most, only striplines could be read out (as described in Sec??), this scan was restricted to the xx mm region between the outer two striplnes. Several high statistics samples are taken at a single point on the x MCP, to derive the single-pe, and large signal time resolutions. Finally, we collect data for various operational voltages on the MCPs in order to study gain-voltage relationships as well as the timing dependences.. Analysis A pair of x MCPs are tested in a large vacuum chamber. The two plates are assembled in a glass tray, designed to the specifications of our final sealed-tube design. The base of the tray serves as the anode, Now compressable steel ribbon grid-spacer MCP grid-spacer MCP grid-spacer glass anode tray breadboard Figure : Illustration of the MCP test-chamber. SMA and HV feedthroughs turbo pump vacuum region mirror incoming laser beam quartz vacuum window " MCP stack vacuum chamber Figure : A schematic of the MCP test chamber. Figure : Illustration of the MCP test-chamber. at IIT, Chicago Preprint submitted to Elsevier screw cross-bar aluminum coated, quartz window Here we report on our algorithms and analysis techniques. February, Voltage, mv σ =. psec events Noise Signal Events / ( psec) Fourier Transform, d Frequency, GHz gain..... Time, nsec Time, nsec Figure : Pulse height distribution Figure : Frequency spectrum of the MCP signal plus noies (blue) overlaid on the pure noise spectrum (red). Signal dominates over noise onlyup to around MHz. Figure : Transit Time Spread. Results Fourier Transform, d Two different kinds timing measurements are presented in this paper:.) measurements of the absolute arrival time of the signals from each side of the stripline with respect to an external trigger signal, and.) measurements of the arrvial times of the two signals with respect to each other. In either case, filters are used to remove the high-frequency noise and a simple Gaussian is fit to the rising edge of the signal. In the case of the differential timing measurement, the signal and noise spectra are nearly identical, as is the shape of the pulse. For the absoute timing measurements, the fast photodiode used as an external trigger contains different noise and signal spectra from each of the MCP traces. This necessitates different approaches for each of these two cases. A typical example of the pulse shape is shown on Fig.??. There is a fast rising edge (approx. xx psec) and slower falling edge with broad tail. Here we report on the results... Differential Time-Resolution We define the differential time-resolution.. Large Signal ehavior Noise Signal.. Gain Figure shows pulse height distribution. Frequency, GHz.. Review of the Factors that Limit MCP Time Resolution Time resolution of MCP-PDs is determined by characteristics of the readout system, intrinsic jitter in the time response of the MCPs, and on the algorithm used to reconstruct the arrival time. Limitations of the readout system can be parameterized in terms of four key variables: analog bandwidth, sampling rate of the readout electronics, noise-to-signal (N/S), and he rise time of the signals. Intrinsic jitter in the MCP is driven by fluctuations in the first stage of avalanche formation in the MCP and, in particular, the first strike position of the first photoelectron with the MCP pore. The larger the pore diameter, the wider the possible variation of the first-strike position. Figure : Frequency spectrum of the trigger signal plus noies (blue) overlaid on the pure noise spectrum (red). The trigger signal is larger than that of the noise over a much wider frequency range, into the multi-ghz range... Transit Time Spread Figure shows the single photoelectron transit time distribution for one particular position on the MCP detector. We fit this distribution with a Gaussian over a range of +- sigma about the peak. The arrival time resolution is thus determined to be +- (stat) picoseconds. This position was chosen arbitrarily as the reference point for collecting high statistics, single PE data. However, lower statistics data was collected at a variety of other points on the detector. Table?? shows the arival time resolution measured at various points on the detector surface and Fig?? identifies the approximate locations of each of these data sets. These measurements cover a large range of locations in the direction parallel to a single stripline. However, in the transvers direction, we are limited to the range spanned by the four consequative microstriplines accessible to us with vacuum feedthroughs. σ =. psec events As discussed in Sec??, timing characteristics of an MCP detector are expected to improve with signal size. In the limit of N/S, uncertainty on the readout is expected to approach. A good proxy for this uncertainty is the differential time resolution, where intrinsic jitter in the time response of the MCP shows up as a common phase on both sides of the readout, and is subtracted away when we take the difference. Uncertainty in measuring the absolute arrival time of the signal, depends not only on the N/S, but the intrinsic jitter of the MCP response. Even with excellent N/S, singe PE data will be dominated by this jitter, which can only be reduced by increasing the number of photoelectrons. Our data, even when taken with arbitrary light intensity, was dominated by single PE pulses with a small number of pulses with a few PEs. Thus, when we bin our data by N/S, we expect our differential time resolution to improve linearly, approaching for very small N/S, and we expect the absolute time resolution to be dominated by MCP jitter which is estimated to be O() psec for µm Events / ( psec) Figure : An example of our shape-based pulse fit. Pulses are fit with a Gausian over the range from % of the pulse peak, up to and including two points past the signal maximum. Time difference, psec Figure : The differential time resolution for a large-signal sample. relative transit time (seconds) - Similarly, the absolute arrival time resolution as a function of N/S was measured. This resolution improved as N/S approached. However, the extrapolated resolution for N/S= was roughly picoseconds. This limit is likely due to intrinsic jitter in the time response of the MCPs, which were operating close to single PE mode. This jitter in arrival time resolution would scale as / N with the number of photoelectrons. Thus, for time-of-flight applications, we expect absolute time resolutions approaching the few picosecond range. Future improvements to MCP design, such as smaller pore sizes, are expected to improve this intrinsic jitter. References Time resolution, psec..... CFD Fit CFD & Filter Fit & Filter y =. +.x y =. +.x y =. +.x y =. +.x. Inverse pulse amplitude, V PC Voltage (v) ). Figure : Absolute time resolution plotted as a function of noise/signal for single photoelectron data. In the limits of large signal, the time resolution is estimated to be O() picoseconds due to intrinsic jitter in the MCP time response. In the limits of many photoelectrons, this resolution is expected to scale as (/ NP E Figure : Transit Time Spread as a function of parameters (dummy - MCPs - & Apr, Differential ( ends) resolution, s..... N/S... Figure : Differential time resolution between the two ends of the delay-line anode as a function of noise/signal compared with simulations (in blue). In the limits of large signal this curve approached sub-psec time resolutions. (dummy) [] J. L. Wiza, Microchannel plate detectors, Nucl. Instrum. Methods (). []. O. Siegmund, Paper on resoultion. [] J. Milnes, J. Howorth, Picosecond time response of microchannel plate pmt detectors, Proc. SPIE (). [] M. Akatsu, Y. Enari, K. Hayasaka, T. Hokuue, T. Iijima, K. Inami, K. Itoh, Y. Kawakami, et al, Mcp-pmt timing property for single photons, Nucl. Instrum. Methods A (). [] K. Inami, N. Kishimoto, Y. Enari, M. Nagamine, T. Ohshima, A -ps tof-counter with an mcp-pmt, Nucl. Instrum. Methods A (). []. O. Siegmund, Paper on gain. []. O. Siegmund, Paper on noise. [] S. George, Atomic layer deposition: An overview, Chemical Reviews (). [] S. Jokela, I. Veryovkin, A. Zinovev, J. Elam, Q. Peng,, A. Mane, The characterization of secondary electron emitters for use in large area photo-detectors, Application of Accelerators in Research and Industry AIP Conf. Proc. (). [] N. Sullivan, P. de Rouffignac, D. eaulieu, A. Tremsin, K. Saadatmand, D. Gorelikov, H. Klotzsch, K. Stenton, S. achman, R. Toomey, Novel microchannel plate device fabricated with atomic layer deposition, Proceedings of the Ninth International Conference on Atomic Layer Deposition. [] H. Grabas, R. Obaid, E. Oberla, H. Frisch, J. Genat, R. Northrop, D. McGinnes,. Adams, M. Wetstein, Rf striplineanodes for psec large-area, mcp-based photodetectors, Nucl. Instrum. Methods.. Conclusion A working x Microchannel plate detector system, consisting of ALD-functionalized MCPs and an economical, scalable microstripline anode were tested with a fast, pulsed laser. The detector exhibited a pulse height distribution peaked at gains. Single photoelectron transit time spreads as low as picoseconds and consitently below picosends were observed at a variety of locations on the detector. The differential time resolution between the two ends of the microstripline anode was determined to be picoseconds for single PEs, corresponding to roughly cm spatial resolution in the direction parallel to the strips. In the transverse direction, position was determined using the signal centroid on a cluster of strips. The width of this centroid, corresponding to the transverse position resolution of the detector was mm. These single PE characteristics are excellent for use in applications where diffuse optical light is used to reconstruct charged particle tracks. For collider applications, where time-of-flight is determined by measuring the light of a high energy particle travelling through a radiator, producing O() photoelectrons in a single spot on the detector, the large-signal resolution is much better. We studied the scaling relationship between signal size and time resolution for both the arrival time resolution and the differential resolution. Differential timing depends only on the RF characteristics of the anode and readout, and the signal-tonoise ratio of the pulse. Jitter in the time response of the MCP itself shifts both sides of the signal by a phase, which is subtracted out when we take the difference. Thus, we expect the differential time resolution to approach in the limit where N/S approaches. Measuring the differential time resolution binned by N/S, we observed. picoseconds in the bin with largest signal. Plotting differential time resolution as a function of N/S, we obtain a linear relationship with an intercept of. picoseconds for N/S=. This matches closely with our simulated trendline. The offset of. psec is explainable as a consequence of our finite laser spot size of. mm. Demountable Should be enough material for a paper. Hope to start work on that soon. Next steps for the demountable are unclear...