1. MCP Analysis on ALpha
Howard Chiao

2. Outline What experiment do you work on? What are its goals?
What has your role been?
What have you accomplished?
What remains for you and your successor?

3. What Is ALPHA? Antihydrogen Laser PHysics Apparatus
Located at the Antiproton Decelerator (AD), a storage ring at CERN
Collaboration between 14 universities and 7 countries

4. What Does ALPHA Do?
Mixing positrons and antiprotons to create antihydrogen in low temperature
Trap antihydrogen in a magnetic trap
Test CPT symmetry through comparison of the atomic spectra
Find out the interaction between gravity and antimatter

5. What Does ALPHA Do?

6. How To Get Positron?
ALPHA uses the positron produced in the beta-plus (e+) decay of sodium-22 atoms.
Collides with nitrogen molecules to lose energy by producing an excitation of nitrogen.
Positrons are then sent to the accumulator.

7. How To Get Antiproton?
Get a bunch of particles from targets, and select pbars by charge and mass ratio.

8. The Setup of ALPHA Apparatus

9. Penning Trap A widely-used charged particle trap
Uniform magnetic field
Quadratic electric
potential

10. Magnetic Trap
Trapping neutral particles with magnetic dipole moments (ex. Antihydrogen)
Only antihydrogen with temperature lower than 0.5K can be trapped.

11. Microchannel Plate Detector (MCP)
The “camera” of particle beams.
An array of small electron multipliers
Large potential difference across
Particles are accelerated onto a phosphor screen to produce light.
Front -> back -> phospher
PMT: numbers in spill logs (scintillator -> light -> PMT -> electrical signal)

12. My Project
Image recognition and analysis for two circles

13. Other Responsibilities
Taking shifts
Assembling zombie computers
Helium transfer
Hardware setup (e.g. MCP Voltage Test, PMT, Soldering, Plumbing, etc. )
Optimize beam (e.g. Running Sequences)
Temperature Analysis for Pbar and e+
Trapping Analysis for antihydrogen
Baselines
Soldering : connection between computer and the electrical nodes
Plumbing: a hose came off during shifts…

14. Helium Transfer
Get two new ones everyday. Helium for the atom trap

15. Plumbing

16. Setting Up PMT9

17. Soldering

18. Sequencer
Interface to control the experiment

19. TDiag – Temperature Measurement
Voltage
Positrons trapped here t1
Position

20. TDiag – Temperature Measurement
Voltage t2
Position

21. TDiag – Temperature Measurement
Voltage t3
Position

22. Half Load, RW, EVC 100%, TDiag # of particles vs. energy (i.e. time)
Data: charge deposited on MCP (mode1: produce light to take picture, mode2: FC)

23. Full Xfer, Cool, RW, Ekick, TDump
Right top similar as p22.
Left bottom: ramp file
Left top: Counts vs. time
Data: dump to MCP because it’s solid, and PMT detects
Stick: egun, FC, MCP, a hole, …

24. Analyzing Trapping Data
1% chance to be cosmic ray

25. Analyzing Trapping Data
1% chance to be cosmic ray

26. Passed-Cut
1% chance to be cosmic ray

27. Cosmic Ray
1% chance to be cosmic ray

28. Non-Trivial
1% chance to be cosmic ray

29. Working on: CUDA for Faster Analysis
A parallel computing platform and programming model invented by NVIDIA.
Enables dramatic increases in computing performance by harnessing the power of graphical processing unit.

30. Current GPU Analysis Interface

31. Thank you, Steven and Jean, for giving me this enriching experience, precious time in Europe and exposure to the best antihydrogen experiment in the world.
Thank you, my fellows, for teaching me useful conversational English and make me laugh all the time together.

32. Question for Tim Why different analysis software for e+ and pbar?
Verify EVC and why half load