Pos(PD07)018

PoS(PD07)018

http://pos.sissa.it che diode, as well as itivity. Due to careful to careful itivity. Due alkali photocathode (ultra . In this article, recent. advancementsof 5 chain, an avalanche diode is incorporated in in is incorporated diode an avalanche chain, of photocathode sens photocathode of ate a photocathodeate a a dynode and chain for r R7600, quite high compared to 27 % of 27 % to high compared quite r R7600, hotocathode and the avalan and the hotocathode quantum efficiency of bi efficiency of quantum eative Commons Attribution-NonCommercial-ShareAlike Licence. Licence. Commons Attribution-NonCommercial-ShareAlike eative low darkcountrate of a few thousands Hzor less cannot be

1 [email protected] [email protected] Photomultiplier tubes (PMTs), which incorpor Motohiro Suyama Motohiro Suyama using avalanchea small diode for response. fast time a single-photon This HPD shows timing 10 of gain high a and FWHM in ps 50 of resolution electron multiplicationby are featuredgain highdetect in vacuum, to a single photon and fast response of time nano second with large effectiveup areato 20 inches.Single-photon detection at area large effective with such achievedbydevices. any other still usefulvarious Therefore,for applications, PMTs are such as high-energybiology, as industry chemistry, well physics medical, as experiments. Varieties of PMTs inphotocathode effective area, and material electron multiplication are mechanisms individualavailablefor purpose,furthermore, are still evolving the the PMTs satisfy to physics. high-energy as such science, frontier advanced from requirements jump is a big achievements recent of the One conventionalAnotherones. challenge hasbeenon done electron-multiplication stagerealize a to dynode the of Instead (HPD). photo-detector hybrid by developed been just has HPD A high-speed electrons. multiply and receive to a tube adjusting of transit time the electronsfrom p control of the photocathode process, the peak peak the process, photocathode of the control fo 43 %, for bialkali, UBA) reaches example PMTs and relateddescribed.will be sensors 1 Copyright ownedCopyright by the author(s) under the terms of the Cr

Motohiro Suyama K.K. Photonics Hamamatsu Division, Tube Electron 314-5 Shimokanzo,Iwata, Japan E-mail: Latest status of PMTs and related sensors of PMTs and related Latest status

PoS(PD07)018 M. Suyama M. Suyama for bialkali photocathode for bialkali photocathode 2 tatic focusing lens in vacuum is used to tatic focusingin vacuum lens ve rooms to be improved.quantum The high-energy physics. In this article, recent high-energyIn this article, physics. le for most of applications. Thanks to this of applications. Thanks to this le for most e 10, 13 or 20 inches are size, such as 8, than due to small thickness pico second [2] e conventional PMTs is that theyconventional cannot be e or higher and are output from the anode. A the anode. are output from and higher or hode with higher quantum efficiencyhode with higher quantum is e various applications, such still useful for as 6 PMTs are shown, as well as operational shown, as PMTs are of single photon is easily achieved at timingof single photon chain deteriorates timing resolution of incident resolution of incident deteriorates timing chain the PMTs are still evolving to satisfy the evolving to satisfy the PMTs are still rate of a few thousands Hz of a rate be orless cannot

. Since a photocathode is . Since made by a reaction of 6 e secondary electron multiplication. With 8 or 108 or With e secondary electron multiplication. 2 2 lated sensors will be shown. second with large effective area up to 20 inches. Single-photon detection detection Single-photon effective second with large up to 20 inches. area

multiplication in vacuum, are vacuum, featured by in to detect high gain multiplication a single fast photon and PMTs PMTs of In this section, recent advancements Introduction Introduction A dynode chain is a series of electrodes calledA dynode chain dynode. Each dynodemultiplies In the case of large format PMT, an electro-s Structure and common features of PMTs tube is a vacuum PMT [1]. 1 Figure shown in PMT is A sectional drawing of typical Contrary still to these versatilities, PMTs ha

Photomultiplier tubes (PMTs), which incorporate a photocathode and a dynodeand a photocathode tubes (PMTs), which incorporate chain for Photomultiplier

at room temperature;at room very devices sensitive to single comparing with semiconductor low photons. Response time of the photocathode is less of several tens nm. as th 5, for example, electrons bya factor of dynodes, electrons are multiplied by a factor of 10 2. 1. Latest PMTs Latest alkali vapor, such as potassium and/or cesium, larg and/or such as potassium alkali vapor, available. Dark current from the photocathode is 0.01 to 0.1 Hz/mm to the photocathode is 0.01 available. Dark current from transit time spread of electrons through a dynode spread of electrons through transit time photon by or less; acceptab an order of nano second high gain and high timing resolution, detection detection resolution, timing high high gain and resolution of less than nano second. resolution of with such large effective area at low dark count with such large effective achieved by any devices. Therefore, other ar PMTs chemistry,biology, medical, industry well as high-energy as physics experiments. Varieties of and electron area, material photocathode PMTs in effective multiplication mechanisms are purpose, furthermore, available for individual of PMTs and re advancements electron of nano response time requirements from advanced science, such as frontier from requirements principle and general features. general features. principle and 2.1 dynode and a photons to incident electrons in response emit to a photocathode incorporating chain to electrons bymultiply a factor of 10 combine a photocathode of large area and a dynode chain. Electrons from the photocathode are the photocathode from Electrons chain. large area and a dynode of combine a photocathode on electric of flexibility kind This 2. Figure shown in as dynode, smaller a much focused on for finely tuned useful and more be more tube it possible for PMTs to makes vacuum field in each application. efficiency of normal photocathode has been 20 to 30 %. Thus, only a part of photons can be can photons part of a only Thus, %. 30 to been 20 has photocathode normal efficiency of converted to electrons comparing with chain is bulky,at the photocathode. The dynode devices. Another disadvantage of th semiconductor distorted by the field. In the magnetic field, is seriously operated in a because electron trajectory photocat recently developed following sections, PoS(PD07)018 M. Suyama M. Suyama

77 ~10 ~10 66 TotalTotal gain: gain: 10 10 PMT are focused on the dynode by electro- by dynode the on focused are PMT

has succeeded to develop a photocathode of of has succeeded to develop a photocathode incorporates a photocathode and a dynode chain chain a dynode photocathode and a incorporates bility of recombinationexited electrons for Therefore, there is optimized thickness and there is optimized Therefore, one for 550 to 800 nm. As shown here, the 800 nm. for 550 to one as well as equi-potential,as is shown. ocathode. Figure 3 shows spectral sensitivities is discussed in termsis discussed of better timing resolution ectral responses calledof such photocathodes

3 3 5 5 x 5xx 5x 5 5 DynodeDynode chain chain in a vacuum envelope. vacuum in a ElectronElectron lens lens PhotocathodePhotocathode static focusing lens. Electron trajectory, static focusing Electrons from the photocathode of large format of large the photocathode from Electrons

Sectionalof drawing a typical PMT, which Recently, one of our optimization methods optimization of our Recently, one

Improvement of the photocathode sensitivity sensor to parts of PMTs as a photon important the one of most is A photocathode

Figure 1: Figure Figure 2: 2: Figure 2.2 electrons. The excite to a photocathode absorbed in are electrons. Photons to translate photons In to general, thicker photocathode vacuum. electrons travel to the boundary and emitted efficiently, more absorbs photons however, proba increases rapidly before reaching the boundary. the before reaching increases rapidly phot for high-sensitive of materials composition of conventional photocathodes. In general, a bialkali photocathode is used to detect 400 nm- detect 400 is used to photocathode a bialkali general, In photocathodes. of conventional photons, whereas a multialkali or extended red shows sp 4 efficiency. Figure higher quantum %, in spite of such optimization. quantum efficiencymaximum of such optimization. is 20 to 30 %, in spite super bialkali (SBA) and ultra bialkali (UBA). In the case of R7400 series, the maximum the UBA. At this moment, with to 46 % 27 % from a big jump efficiency made quantum Latest PMTs Latest A PMT using as well. is shown dynode low-profile a panel PMT using A flat introduced. microchannel instead plates chain of the dynode and applicability in a high magnetic field. magnetic in a high and applicability PoS(PD07)018 m can μ M. Suyama M. Suyama ) and ultra ultra ) and 700 ission is high. As ission is high. As a 600 multialkali Extended red (SBA) i Super bialkali Super (UBA) 500 Multialkal Ultra bialkali

y of photo-electron em y of photo-electron is limited, because optimization depends on depends optimization because is limited, going to expand the availabilitygoing to these of cathode reaches 50 % at visible region. The % at visible region. cathode reaches 50 R7422 series with 5 moment, diameter mm [3], ited, because different activation process from ited, because different

4 4 Wavelength nm 400 Wavelength (nm) Wavelength Conventiona efficiency is shown. efficiency is shown. extendedmultialkali red are shown. 300 Bialkali 200 0

40 30 20 10 50

200 300 400 500 600 700 800 900 1000 1 ) Efficiency Quantum 10 0.1

100

Quantum of conventional efficiencies photocathodes, suchbialkali, as multialkali, and Quantum efficiency (%) efficiency Quantum (SBA bialkali super called photocathodes bialkali new of efficiencies Quantum

For the higher quantum efficiency crystal green or red region, semiconductor quantum in For the higher Figure 3: 3: Figure Figure 4: Figure bialkali (UBA) are shown, referring to R7400 series. Big jump of 27 % to 46 % at the maximum quantum quantum maximum the % at 46 % to 27 of jump Big series. R7400 to referring are shown, (UBA) bialkali be used to absorb more photons. more be used to absorb As GaAs or GaAsP crystals show negative electron affinity when they the probabilit are activated by cesium, The Figure 5. as shown in are high, photocathodes efficiencies of these result, quantum efficiency quantum maximum of GaAsP photo is verylim photocathodes availability of these is necessary.photocathodes At this conventional or R10467 series (HPD) diameter withare the mm 3 only choice. photocathodes for variety of PMTs. for varietyof photocathodes Due to good qualityphotocathode is useful. of these crystals, life of exited electrons is time as thick as 1 Thus, a photocathode photocathode. longer than that in alkali-based much detailed structuredetailed of PMTs. is Hamamatsu Latest PMTs Latest the other PMTs SBA or UBA to of application PoS(PD07)018 nodes as A. The A. The M. Suyama M. Suyama n. n. 16x16 pixels pixels 16x16 is called as a metal channel is called as a metal of thin etched plates was developed. of thin etched plates was developed. GaAs ated to develop so called flat panel PMT, panel PMT, called flat ated to develop so tal photocathodes are shown with UB with shown are photocathodes tal

sors are available, such as R7600 series, series, sors are available, such as R7600 h requires fine segmentations such as high- h requires fine segmentations 1.5mm to establish a bunch of individual dy to establish a bunch of individual rise and fall times of the order of nano second. rise and fall times of the order

mm-length (R7400 series) aremm-length realized. Because Models of 8x8 pixels (H8500) and Models of 8x8 pixels nnel of electrons, and nnel of 5 5 dynode. dynode. Wavelength (nm) Wavelength GaAsP 12mm ely assembled ely assembled UBA 200 300 400 500 600 700 800 900 1000 1 10 12mm 100

φ Quantum efficiency (%) efficiency Quantum Quantum efficiencies of semiconductor crys of semiconductor efficiencies Quantum

ximum quantum efficiency of GaAsP photocathode reaches 50 % in visible regio visible % in 50 reaches photocathode GaAsP of efficiency quantum ximum

Sectional drawing of R7400 series shows detailed structure and operation of metal channel channel metal of operation and structure detailed shows series R7400 of drawing Sectional etal channel dynodes ma

M made chain In order to realize small PMT, a dynode The metal channel dynode was further investig ) [5] whic are available for applications ) [5] . Thanks to this structure, PMT with 12 to this structure, . Thanks Figure 5: Figure

Figure 6: Figure (H9500

2.3 Latest PMTs Latest of short electron trajectory, R7400 performs fast performs of short electron trajectory, R7400 sen or position sensitive multi-pixel In addition, because incident position of electrons is preserved in the metal channel dynode. and PET. experiments energyphysics shown in Figure 6 [4]. This looks like a cha a looks like This 6 [4]. Figure shown in hed parts of the plates are fin of the Etched parts dynode as shown in Figure 7. Large effective area of 49 mm square compared with the outer dimension effective areaouter dimension Figure 7. Large of 49 mm square compared with the as shown in of 52 mm is one of the features of this PMT. PoS(PD07)018 nel. nel. M. Suyama M. Suyama m, thus the aspect m, μ 0). 0). of very short electron trajectory it is insensitive to magnetic field of up to to magnetic it is insensitive m, is 240 and thickness m, μ 40 % of incident electrons are not multiplied multiplied electrons are not incident of 40 %

for example, between input and output surfaces, surfaces, output input and between for example, photons. Because 6 6 49mm Effective: Effective: Photograph of flat panel PMT (H8500/H950 PMT panel flat of Photograph to detect single to detect 6 52mm Figure 7: Figure 15mm ochannel thin glass plate with plate (MCP) is a of via holes from plenty input to Sectional drawing of MCP shows the way for electrons being multiplied in a chan a in multiplied being electrons for way the shows MCP of drawing Sectional cir

A m MCPsdynodes so called MCP-PMT. Two used for to realize be of MCP can Two layers MCP s good timing resolution of less than 30ps in than 30ps less of resolution shows good timing of the MCP, the MCP-PMT annel hole is 40. With a bias voltage of 1kV, hole is gure 8: Fi

.4 an electron entering a hole is multiplied by successive secondary to be electron a multiplication [6]. in Figure 8 as shown factor of 10,000, 10 of gain high give enough FWHM for single photons [7].sameFWHM for single photons reason, With the 1.8 T, when the field is parallel to the tube axis [7]. is Due to these great features, MCP-PMT to the tube axis [7]. parallel 1.8 T, when the field is One of the drawbacks of MCP is an upgrade [8]. Belle used for TOP counters in studied to be thus approximately, 60 %, open area ratio of efficiently. in a ch

2 Latest PMTs Latest

ratio of output surfaces. Typical diameter of holes is 6 PoS(PD07)018

itted from M. Suyama M. Suyama sed on the avalanche sed on the avalanche ing the photo electrons ing the photo electrons one electron-hole pair is pair is one electron-hole , high enough to detect single 5 Figure 9. Electrons em Figure 9. Electrons Electron-Bombarded Gain is a factor of 100 gain at the higher Electrons Avalanche Gain Gain Avalanche Avalanche Diode (AD) their kinetic energy the AD, and generate their in on by in the AD to be further an electric field rated close to the surface (order of nm). surface (orderrated of nm). close to the number of electrons from the photocathode. of electrons from number s are accelerated and focu

can be used for multiply Photocathode This makes almost noiseless multiplication of 7 7 energy in a silicon device, a silicon energy in Photons Output HPD sho HPD 3.6eV in average. This process 3.6eV in average.

D) by lens. Electrons deposit an electron Schematic drawing of of drawing Schematic of thousands generate AD the entering electrons that ws en electrons deposit their kinetic their deposit When electrons Hybrid Photo-Detector (HPD) Photo-Detector Hybrid

The advantage of the HPD compared with PMTs Structure and common features of HPD s, and gives a capability to distinguish ical structure of HPD Typical structure of HPD is schematicallyshown in of a dynode chain. The photon sensor incorporating a semiconductor device facing the facing the device incorporating a semiconductor sensor chain. The photon of a dynode A

. .1 Simple structure of HPD has a potential to be high speed, as shown below. speed, structure of HPD has a potential to be high Simple first gain stage; electron-bombarded first gain stage;gain. electron-bombarded photons. Non linear part Non at the low energyphotons. part can be explained by rapid recombination of carriers at surface states, because carriers are gene generated per instead diode ( electro Figure 9: Figure electron-hole pairs at the first point,electron-holefirst pairs at the and these electronsfurther multiplied are by avalanche multiplication. Latest PMTs Latest 3 the photocathode in response to incident photon the photocathode multiplied by a factor of 100. Then, the total gain reaches 10 total 100. Then, the by a factor of multiplied photocathode is called a hybrid photo-detector (HPD). Performance of a high-speed HPD of a (HPD). Performance high-speed is called a photo-detector photocathode hybrid as well as general featuresdeveloped recently, is reported in this section. the HPD, of 3 of energy to landing electron-hole pairs. Number of electron-hole pairs is linearlyproportional at 8 keV. These electrons, except to 2,000 energy then 2keV, and is typically 1,500 lower electrons are drift to the avalanche regi multiplied PoS(PD07)018 M. Suyama M. Suyama 10 to the AD, and using small AD for fast AD for fast and using small to the AD, of -8kV, and the avalanche gain is 110 at gain is 110 at of -8kV, and the avalanche er. This apparently indicates imperfection of er. This apparently indicates imperfection of 50 ps in FWHM for full illumination, and 33 for full illumination, 50 ps in FWHM tal gain reaches 180,000,tal gain reaches where the electron-

8kV. 8kV. 8 8 Photocathode Applied Voltage (-kV) Voltage Applied Photocathode 02468 0

500

2000 1500 1000 Electron Bombarded Gain Bombarded Electron

Electron-bombarded gain characteristic shows gain of 1600 at the photocathode voltage of - of voltage photocathode the at 1600 of gain shows characteristic gain Electron-bombarded The gain characteristics of both electron-bombardment and avalanche multiplication are are The gain characteristics and avalanche multiplication both electron-bombardment of High-speed HPDHigh-speed transit time fromAdjusting photocathode the

Figure 10: response, the high-speed HPD was designed and manufactured [9]. A bialkali photocathode of 8 of bialkali photocathode A [9]. was designed HPD response, the high-speed and manufactured fabricated is round-shaped the photocathode Electrons on the faceplate. mm in diameter from AD of 1 mm in diameter.are focused on the 11, respectively. 10 and shown in figures To gain at the photocathode voltage is 1600 bombarded ps, respectively, 340 are 360 and light The rise AD. 405V to the short pulsed and fall times for capability to for several photons indicates spectrum Pulse height 12. as shown in Figure 13. The timing Figure as shown in the photocathode, 6 electrons from to up distinguish to be single photons was measured resolution for of 1 mm diamet of central area ps for illumination is ps of 50 resolution timing however, over entire photocathode, transit time of the adjustment ps, approximately. fastest PMT of 200 better than the Latest PMTs Latest 3.2 PoS(PD07)018 M. Suyama M. Suyama nctionthe bias of voltage to the AD.

Rise Time Time : Rise 360 ps ps : 340 Time Fall Time (ns) Time 9 9 Output waveform for impulse-light input. input. impulse-light for waveform Output AD Reverse Bias Voltage (V) Voltage Bias Reverse AD Figure 12: 0 100 200 300 400 500 012345 Avalanche gain characteristics as a fu as characteristics gain Avalanche 0 0

60 50 40 30 20 10

50 -10

350 300 250 200 150 100 (mV) Voltage Output Avalanche Gain Avalanche

Figure 11: Latest PMTs Latest PoS(PD07)018 M. Suyama M. Suyama , 2007. , 2007. , 2006. of them has a GaAsP photocathode of 18 18 has a GaAsP photocathode of of them pixel type The last one was reported in [12]. are still evolving continuously satisfying the the are still evolving continuously satisfying the recent advancements are the recent advancements shown above. ing developed for water Cherenkov counter of water Cherenkov counter developed for ing other has a bialkali photocathode of 60x60 mm of 60x60 other has a bialkali photocathode

single photons, appeals its capability, and rapidly its capability, and rapidly single photons, appeals , Rev.Sci. Instrum.," 58932-938,pp. (6), 1987. 10 10 , 2006. H9500 photoelectrons. photoelectrons. Output Pulse Height Output Pulse Femtosecond streak tube streak Femtosecond 0 500 1000 1500 2000 2500 3000 3500 4000 The pulse heightThe pulsefor photonsspectrum multi peaks clearly shows corresponding up to 6 0

350 300 250 200 150 100 Frequency In spite of long history of 50 years, 50 PMTs of In spite of long history Summary Summary

HPD under development Several HPDs are under development now. One Several HPDs are under development

Catalogue of Hamamatsu photonics K.K., R7400U SERIES K.K., , 2004. photonics Hamamatsu of Catalogue K.K., photonics Hamamatsu of Catalogue MCP & MCP assembly & MCP K.K., photonics Hamamatsu of Catalogue K. Kinoshita et al., Kinoshita K. Catalogue of Hamamatsu photonics K.K., PhotomultiplierTtubes K.K., photonics Hamamatsu of Catalogue MODULES TUBE PHOTOMULTIPLIER K.K., photonics Hamamatsu of Catalogue

Figure 13:

[4] [5] [6] [2] [1] [3] References References 4. 3.3 Latest PMTs Latest requirements from all science frontiers. Some of frontiers. Some all science from requirements device to detect HPD, a new type of vacuum expands its application these days. expands its application these mm in diameter for MAGIC telescope [10]. The The mm in diameter for MAGIC telescope [10]. status is aerogel RICH counters. Current developed for pixel, being AD of 12x12 facing to the HPD, 8x8 Regarding multi-pixel shown in ref [11]. be 13 inches photocathode of has a large format [13]. the next generation PoS(PD07)018 , , M. Suyama M. Suyama , International , International Photodetector With High Quantum , Nucl. Instrum. MethodsA579, pp.42-45, PHOTOMULTIPLIER TUBES,PHOTOMULTIPLIER Third edition 51, No.3, pp. 1056-1059, 2004. 2004. 1056-1059, pp. No.3, 51,

11 11 , International workshop on new photon-detectors PD07 PD07 photon-detectors new on workshop , International 2006. , IEEE Trans. Nucl. Sci., vol. Sci., Nucl. Trans. IEEE , High-speedHPD for photon counting,Conference record of IEEE Nuclear Development of a Multipixel Hybrid of a Multipixel Development Large-aperture hybrid photo-detector hybrid Large-aperture Development of 144 multi-anode HPD for Belle aerogel RICH photon detector Timing properties of MCP-PMT of properties Timing Favourable properties of HPD R9792U-40 for the MAGIC telescope project telescope MAGIC the for R9792U-40 HPD of properties Favourable

International workshop on new photon-detectors PD07 (this workshop). workshop). (this PD07 photon-detectors new on workshop International et al., M. Suyama Efficiency andGain Y. Kawai et al., et al., Kawai Y. 2007. workshop on new photon-detectors PD07 (this workshop). workshop). (this PD07 photon-detectors on new workshop I. Adachi, T. Saito, 2005. Technical handook of Hamamatsu photonics K.K., K.K., photonics of Hamamatsu handook Technical K. Inami, (this workshop). A. Fukasawa et al., et Fukasawa A. Symposium, Science

[8] [7] [9] [12] [13] [11] [10] Latest PMTs Latest