1. Argonne National Laboratory Operated by The University of Chicago for the U.S. Department of Energy Applications of psec TOF in proton and heavy-ion accelerators Peter Ostroumov Pico-Sec Timing Hardware Workshop November 18, 2005

2. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 2 Outline ● TOF measurements in accelerators ­Rare Isotope Accelerator Facility ­Accelerated bunched beam velocity (energy) measurements based on induced rf signals ­Bunch time profile measurements with resolution ~10 picoseconds based on streak camera ● Improvement of time resolution of the existing BLD ● Bunch time structure measurements using X-rays ­High resolution is obtained by using streak cameras ● Examples of TOF technique application in nuclear physics experiments at ATLAS: mass and nuclear charge identification of radioactive ions using gas-filled magnet

3. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 3 TOF systems ● High-power (hundreds of kilowatts) accelerators such as RIA driver linac ­Require high-precision control of beam energy ­Maintain short bunches (~40-100 picoseconds) ● Beams of rare isotopes must be analyzed by detecting individual particles. Fast time measurements (~20 picoseconds resolution) are necessary to control bunched beam quality ● Absolute energy measurements based on TOF system ­Required for many experiments ­Non-destructive, cheap compared to magnet ­Well suited for beam velocities <0.5c ­Very high accuracy can be obtained ­Wide range of beam currents starting from ~0.3 nA (~10 10 particles/sec) can be analyzed

4. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 4 Absolute energy measurement using resonant TOF system + _ SCR VCX Clock REF RF Control Module Limiter Phase Shifter Attenuator Detector Power Amplifier A error SCR VCX Clock Power Amplifier Preamplifier 40dB RF Control Module Attenuator 20dB FIG. 3. Simplified RF diagram of ATLAS super conducting resonator in accelerating mode. FIG. 4. SCR low-field operation simplified diagram. + _ SCR VCX Clock REF RF Control Module Limiter Phase Shifter Attenuator Detector Power Amplifier A error SCR VCX Clock Power Amplifier Preamplifier 40dB RF Control Module Attenuator 20dB FIG. 3. Simplified RF diagram of ATLAS super conducting resonator in accelerating mode. FIG. 4. SCR low-field operation simplified diagram. 48.505 MHz Beam frequency = 48.500 MHz Resonator frequency =48.500 MHz FEE Phase meter f=48.505-48.500 = 5 kHz FEE

5. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 5 Absolute energy measurement using resonant TOF system

6. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 6 Absolute energy measurement using resonant TOF system ● Precision of TOF measurements: ­Signal – noise ratio ­Phase jitter due to vibration, some thermal effects ­Major contribution –beam phase jitter Phase advance over 9 m – 5400 deg of 48.5 MHz Phase meter precision ~ 0.2 deg TOF=300 nsec ● Accuracy of beam energy measurements: ­Additional effect is the distance between the detectors ­Typical number is  E/E=2  10 -4

7. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 7 High accuracy is achieved by using ● Chain of bunches, signal is integrated in the resonator (msec); ● Mixing of two frequencies in the resonator helps to avoid extra noise that can be accumulated in external circuits ● The bunch phase at 48.5 MHz is directly translated to 5 kHz and minimizes phase meter errors ● Front End Electronics ­Amplitude detection ­Narrow band-pass filter (5 kHz) ­AGC (automatic gain control) amplifier

8. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 8 Bunch Length detector 1-tangstin target wire, 2-collimator, 3-plates of the rf deflector, 4- MCP, 5-phosphor screen, 6-CCD camera,. I(  ) Ion beam , Z U targ Secondary electrons I(X) X 1 2 3 

9. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 9 Electron beam trajectories with no RF applied (streak camera)

10. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 10 Electron beam image on the phosphor with no RF applied Focused electron beam profile Resolution is ~15 pixels Bunch width = 10 deg at 97 MHz=290 picoseconds 15 pixels corresponds to ~10 picoseconds resolution

11. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 11 RF on, bunch image

12. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 12 Bunch time profile ● 58 Ni bunch profile (a) inferred from scintillator signal (b).

13. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 13 Time resolution ● The time required for the emission of secondary electrons ● The time difference, due to the different arrival times of the secondary electrons originating from different points of the wire, at the rf deflector ● The contribution to the detector resolution from the angular and energy distributions of the secondary electrons ● The time of flight of the electrons through the electrostatic field of the plates. ● Finally the RF voltage and rf phase jitter is a very important factor in determining the time resolution of the detector.

14. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 14 Improvement of time resolution of the existing BLD ● Reduce both the entrance and exit slits size down to ~0.2 mm; ● Use single electron mode of measurements. In the single electron mode the problem associated with the finite size of the SE beam will be minimized. ● Reduce the diameter of the wire to ~0.03 mm; ● Increase the voltage applied to the wire up to 15 kV; ● Increase the rf voltage to have large sweeping amplitude on the exit slit; ● Improve electron beam optics to obtain more isochronous trajectories; ● Improve phase jitter of the rf deflector by introducing an external RF synthesized signal generator with a high stability.

15. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 15 Heavy-ion bunch time structure using X-rays  Streak camera Focusing spectrograph for picosecond time resolution of ion beam (adapted from [1]) [1] O.N. Rosmej et al. 30th EPS Conference on Contr. Fusion and Plasma Phys., St. Petersburg, 7-11 July 2003 ECA Vol. 27A, O-1.9C

16. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 16 Typical streak camera being used at electron synchrotrons Time resolution of streak cameras can be less than 1 picosecond

17. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 17 Heavy-ion bunch time structure using X-rays (proposal) ● Ions penetrate the thin target ( 0.1-0.2 mm) and undergo multiple collisions with target atoms. ● Excitation of bound electrons followed by radiative decay gives rise to projectile and target radiation. Decay time ~10 femtosec ● Focusing specrograph with spatial resolution provides high spectral and spatial resolution of the K-shell spectra. ● Streak camera measures the temporal structure of the beam with picosecond resolution.

18. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 18 ATLAS Layout

19. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 19 Mass and nuclear charge identification using gas-filled spectrograph Difficulty: a)The masses are very close b)The same q/m, velocity

20. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 20 TOF for mass and charge identification

21. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 21 Time-of-Flight Measurement with the Storage Ring in the Isochronous Mode (Milan Matos’ presentation)

22. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 22 Signals from the Detector

23. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 23 Time-of-Flight Spectrum

24. Pioneering Science and Technology Pico-Sec Timing Hardware Workshop, November 18, 2005 24 Conclusion ● Time resolution of 3-5 picoseconds is required to tune and operate high-power heavy-ion linacs ● So far the technique remains complex and expensive to provide high resolution ● TOF is a common technique for identification of mass and nuclear charge of rare isotopes. Currently several large facilities are being constructed worldwide to produce beams of exotic nuclei. ● High resolution MCPs can help to reduce the cost of storage rings or spectrographs in future rare isotope accelerator facilities