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R&D on Fine-mesh multi-anode PMT with T.T.S.=100 ps under B  1T

R&D on Fine-mesh multi-anode PMT with T.T.S.=100 ps under B  1T. Contents Introduction PMT structure & Set up Basic performance Experiment results Gain Time resolution Summary. T.Hokuue. Nagoya University, Japan. Multi-anode. Fine-mesh PMT. L24 - .

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R&D on Fine-mesh multi-anode PMT with T.T.S.=100 ps under B  1T

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  1. R&D on Fine-mesh multi-anode PMT with T.T.S.=100 ps under B1T Contents • Introduction • PMT structure & Set up • Basic performance • Experiment results • Gain • Time resolution • Summary T.Hokuue Nagoya University, Japan Multi-anode Fine-mesh PMT L24 - PID meeting @Nagoya Univ. 31.Aug.2002

  2. TOP counter : a new type of Cherenkov Ring Imaging detector Introduction Requirements Operate under magnetic field : B = 1.5T(at Belle )  Single-photon sensitive with high efficiency  Position sensitive : sx1 mm  Transit time spread : sTTS= 100 ps Our candidates Linear-array Multi-anode Fine-mesh PMT Nucl. Instrum. Meth. : A460,326-335,2001. Hybrid Avalanche PhotoDiode (HAPD) Nucl. Instrum. Meth. : A463,220-226,2001. PID meeting @Nagoya Univ. 31.Aug.2002

  3. A fine-mesh PMT exhibits a good position resolution and moderate time resolution for high multiple-photons, but not for single-photon. Under the magnetic field: We focused our effort toenhance the multiplication gain. PID meeting @Nagoya Univ. 31.Aug.2002

  4.  We made 3 different fine-mesh PMTs a , b , g PMT structures Base: Multi-anode Fine-mesh PMT (R6135-L24X) made by Hamamatsu Photonics Company(HPK),Japan • Common structure : - 24 anodes (readout channels) - anode size  26.50.8 mm - # of stages of fine-mesh dynode 24 (a) or 19 (b,g) PID meeting @Nagoya Univ. 31.Aug.2002

  5. Shorterdistance between photo-cathode and first dynode • H.V divider network ratio • Finer mesh size 1. Shorter distance between photo-cathode and the first dynode a: L = 2.5-3 mm b,g:L = 1 mm Transit time: E1: the applied voltage across L L = 2.5-3 mm  t  660 ps L = 1 mm  t  270 ps PID meeting @Nagoya Univ. 31.Aug.2002

  6. 2. H.V divider network ratio b,g: 2:1: … :1 a: 1:1: … :1  (ex.) Line-forcused PMT (R5900-L16)  T.T.S. 100 ps (1: 1:  1:1)   T.T.S. 70 ps (2: 2:  1:1) 3. Finer mesh size a,b: 2000 lines/inch (12.5mm pitch) g: 2500 lines/inch (9mm pitch) The radius reduces with field strength. • The secondary electrons would get to hit fewer dynodes  reduced multiplication gain Using the finer mesh would undo this reduction somewhat!! PID meeting @Nagoya Univ. 31.Aug.2002

  7. Set up • Set up L24 - PID meeting @Nagoya Univ. 31.Aug.2002

  8. Signal shape (-) ADC distributions Basic performance 1. Single-photon sensitive B = 0.4 T , H.V = 2400 V Rise time  1ns The g exhibits a quite clear single-photon peak. Efficiency : 52 % (-a) 63 % (-b) 85%(-g) PID meeting @Nagoya Univ. 31.Aug.2002

  9. 2. Position sensitive Basic performance - setting 1mm-wide slit on PMT’s surface • Anode-distributions(-a) • Signal spread in root-mean-square You can see clearly the field effect at weak field!! The resolution of 0.5mm is dominated by the slit width of 1mm. True resolution might be much better than this. PID meeting @Nagoya Univ. 31.Aug.2002

  10. Multiplication Gain Gain • Relative gain Gain/Gain(B=0T) H.V = 1600 V 6 The  : Gain  5  10 (B = 1.5T, H.V= 3400V) 5 The  : Gain  8  10 (B = 1.5 T, H.V= 2000 V) The g exhibits less reduction and the highest gain at 0.2T. PID meeting @Nagoya Univ. 31.Aug.2002

  11. Time resolution • ADC-sliced time resolution (-,) & time-walk correction -b 0.4T,1.5kV 0.6T,1.7kV 1.0T,2.2kV T.T.S  150 ps at ADC = 175-th ch at  -g 0.4T,2.4kV type g T.T.S  100 ps at B  1T 150 ps at B = 1.5T T.T.S  100 ps at ADC = 180-190 ch PID meeting @Nagoya Univ. 31.Aug.2002

  12. Gain vs. T.T.S.  has rather steeper relation than  Increment of gain by factor of 10  improve T.T.S of 45 ps (-) 30 ps (-) Both PMTs indicate that the multiplication gain of 3-5 10 are required to have a time resolution of 100ps. 7 The time resolution under various conditions are plotted for  and  PMTs. PID meeting @Nagoya Univ. 31.Aug.2002

  13. T.T.S. with Multi-photons (-b) • Multi-photons • 2-photons TTS 80 ps • 3-photons TTS 70 ps • 4-photons TTS 60 ps We already obtained high time resolution for multiple-photons. PID meeting @Nagoya Univ. 31.Aug.2002

  14. Summary Time resolution : 100 ps (B1T) - By developing fine-mesh 24-anodes PMT 150 ps (B=1.5T) - To have a 100 ps resolution under B=1.5T  multiplication gain of 3-5  10 is required 7 - For higher gain and better T.T.S.  byreducing distance between the first dynode and photo-cathode by increasingly appliedH.V. on the first dynode by using finer mesh dynodes - For Multiple-photons … PID meeting @Nagoya Univ. 31.Aug.2002

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