1. Summer Student Sessions
The ALPHA Experiment
Summer Student Sessions
C. Ø. Rasmussen
Aarhus University

2. Program Reasons for antihydrogen research
Goals of the ALPHA experiment
One of the techniques - EVC
Future measurements

3. Antihydrogen research

4. Antihydrogen research
Simplest pure antimatter atomic system
Antimatter equivalence
CPT symmetry
Antigravity?

5. Goals for ALPHA
Long term goal: Precision spectroscopy using the 1S-2S transition
Main goal with current apparatus: Trap antihydrogen (Nature 2010)
Need atoms trapped in the ground state and for considerable time to do spectroscopy (Nature Physics, July 2011)
f(1S-2S) = (34) Hz - Hänsch et al.

6. Trapping antihydrogen
Interaction of an (anti) atom with a magnetic field:
(ground state)
Two kinds of atoms:
Low field seeking
High field seeking
Ground state –> L=0, Pbar angular momentum supressed by ratio of masses
The magnetic moment of the antihydrogen atom is, if it is in the ground state, governed by the positron spin, and has the size…

7. Trapping antihydrogen
So we create a 3-dimensional magnetic minimum (max can’t be)

8. Some challenges Interaction of an (anti)atom with a magnetic field:
(In 1T field)
Constituent particles do not exist freely on earth (or are rapidly destroyed)
Need to create Hbar inside magnetic trap -> Penning trap

9. Trapping antihydrogen
Need of creating Hbar inside trap demands a penning trap in the same place

10. Cool Particles Antiprotons delivered from AD at 5.3MeV
Trappable antihydrogen AD
Degrader
Electron cooling
EVC

11. EVC (Evaporative Cooling)
Coffee in the Break – forced EVC – maxwell distribution

12. Future Ground state hyperfine transition
Switch from low field seeking to high field seeking
Laser access
Antigravity?
Spin-flip (high field seekers). First spectroscopic measurement on pure antimatter atomic system

13. Questions