1 GASTOF Cherenkov with RF Phototube for FP420 Amur Margaryan 1 Timing Workshop Krakow 2010

22 Contents Introduction RF time measuring technique Radio Frequency Phototube Optical Clock H 3 Single Photon Timing Technique GASTOF Cherenkov with RF phototube

33 Introduction Regular timing technique in high energy and nuclear physics experiments: 1) Time information is transferred by secondary electrons - SE or photoelectrons -PE; 2) The SE and PE are accelerated, multiplied and converted into electrical signals, e.g. by using PMTs or other detectors; 3) Electrical signals are processed by common nanosecond electronics like amplifiers, discriminators and time to digital converters, and digitized. Figure: schematic layout of the regular timing technique a)Nanosecond signal processing; Rate ~ few MHz b)The time measurement error of single PE or SE is in range ps (FWHM). c)The time drift is ~1ps/s (mainly due to electronics).

44 1)Time information is transferred by SEs or PEs; 2)The electrons are accelerated and deflected by means of ultra high frequency RF fields; Parameters: a) The limit of precision of time measurement of single SE or PE is σ ≈ 1 ps; b) High and long-term stability fs/h - can be reached; c) Time drift is ~10fs/s; d) Image processing; rate is ~10 kHz. Radio Frequency Time Measuring Technique or Streak Camera Principle or Oscilloscopic Method Figure: Schematic of the radio frequency time measuring technique Image Readout, e.g. by using the CCD

55 Radio Frequency Phototube Operates like circular scan streak camera but provides nanosecond signals like regular pmt CW SE beam Single SE Parameters: a) Timing dispersion is similar to streak cameras b) Provides nanosecond signals like regular PMT; rate ≈ few MHz A. Margaryan et al., Nucl. Instr. and Meth. A566, 321,2006

66 Position Sensitive Anodes Resistive AnodeMulti Pixel Anode

77 RF phototube with point-like photocathode The schematic layout of the RF phototube with point-like photocathode. 1 - photo cathode, 2 - electron-transparent electrode, 3 - electrostatic lens, 4 - RF deflection electrodes, 5 - image of PEs, 6 - λ/4 RF coaxial cavity, 7 - SE detector.

88 RF phototube with large-size photocathode The schematic layout of the RF phototube with large-size photocathode. 1 - photo cathode (for 4 cm diameter photocathode the time dispersion of PE is ≤10 ps, FWHM), 2 - electron-transparent electrode, 3 - transmission dynode, 4 - accelerating electrode, 5 - electrostatic lens, 6 - RF deflection electrodes, 7 - image of PEs, 8 - λ/4 RF coaxial cavity, 9 - SE detector.

99 Uncertainty sources of time measurement with f = 500 MHz RF field 1.Time dispersion of PE emission ≤ 1 ps 2.Time dispersion of electron tube: chromatic aberration and transit time ≤ 2 ps 3. So called “Technical Time Resolution” of the deflector: σ = d/v, where d is the size of the electron spot, v = 2πR/T is the scanning speed. For our case d = 1 mm, R = 2 cm, T = 2 ns ~20 ps TOTAL ~21 ps THEORETICAL LIMIT OF THE TECHNIQUE ~1 ps

10 RF signal- is constant - nominal frequency - nominal phase - deviations: random and systematic RF timing: stand-alone operation, random photon source and

11 Stand-alone operation: periodic photon source 11 drift speed on the scanning circle drift is clockwise drift is counterclockwise Synchroscan mode

12 RF timing: synchroscan operational mode 12 Ideal RF synthesizer and tube Position of photoelectrons stay stable on the scanning circle

13 Time drift: synchroscan mode 13 Time drift of the streak cameras < 10 fs/s W. Uhring et al., Rev. Sci. Instr. V.74, 2003

14 Synchroscan mode: experiment with reference beam Random and Systematic time drifts due to RF Synthesizer and RF Phototube Schematic of the setup Forthey can be ignored and stability will be determined by statistics only For single PE

15 Drift of relative measurements A. MargaryanYerevan,19 May Long-term stability (~200 fs) of streak cameras with reference photon beam W. Uhring et al., Rev. Sci. Instr. V.74, 2003

16 To drive RF phototube RF Phototube and Optical Clock Optical Clock or Femtosecond Optical Frequency Comb Technique Transformed Coherently Optical Frequencies into the Microwave Range Schematic of the optical clockwork, J. L. Hall, Nobel lecture, 2005

17 Femtosecond Optical Frequency Comb as a multipurpose frequency synthesizer, Depicted from T. M. Ramond et al., 2003 Fractional instability of optical clocks  Fractional instability of rf synthesizer <  

18 RF phototube + optical clock = 3H timing technique for single photons 18 Schematic layout of the synchroscan mode of RF phototube with optical clock. Optical Clock is used as a source of RF frequencies to operate the RF phototube and as a reference photon beam to minimize or exclude the time drifts due to RF synthesizer and phototube. Time precision determined by single photon time resolution and statistics !!! A. Margaryan, article in press, doi: /j. nima,

19 Conclusions Radio Frequency Phototube + Periodic Photon Source (Accelerator, Optical Clock etc) = H 3 Single Photon Timing Technique High resolution, 20 ps for single PE (limit ~ ps) High rate, few MHz Highly stable, 10 fs/day

20 Applications Nuclear Physics: Absolute calibration of the magnetic spectrometers; Precise mass measurements; delayed pion spectroscopy of hypernuclei; precise lifetime measurements Fundamental Tests: Gravitational Red-Shift Measurement; Light speed anisotropy Biomedical applications Diffuse optic imaging; Fluorescence lifetime imaging; TOF-PET Other applications Quantum cryptography

21 Cherenkov Time-of-Flight (TOF) and Time-of- Propagation (TOP) Detectors Based on RF Phototube The time scale of Cherenkov radiation is ≤ 1ps, ideal for TOF The schematic of Cherenkov TOF detector in a “head-on” geometry based on RF phototube RF Cherenkov picosecond timing technique for high energy physics applications, A. Margaryan, O. Hashimoto, S. Majewski, L. Tang, NIM, A595, 2008, 274

22 Time distribution of p = 5000 MeV/c pions in “head-on” CherenkovTOF detector with L = 1 cm quartz radiator. a) Time distribution of single photoelectrons b) Mean time distribution of 150 photoelectrons c) Mean time distribution of 100 photoelectrons

23 Fast Timing for FP Luminosity Timing Resolution ps 10 5 Event rate at maximum luminosity is ~ 10 MHz Few events in a 1ns time interval is needed to be detected Time stability ~ 1ps

24 GASTOF Cherenkov Schematic of the GASTOF Cherenkov ant its intrinsic time resolution. Depicted from the FP420 R&D Project

25 GASTOF Cherenkov with RF phototube Schematic of the GASTOF Cherenkov with RF phototube

26 Readout Electronics Schematic of the Readout Scheme with Multi Pixel Anode The expected at maximum luminosity 10 MHz rate the RF deflector is distributed among ~100 pixels. Each pixel will operate as an independent PMT with ~0.1 MHz rate.

27 Conclusion GASTOF with Radio Frequency Phototube Intrinsic Time resolution few ps Rate 10 MHz Stability < 1 ps/hrs Ability to detect several ten events in a ns period

28 THANK YOU