1. The ALPHA Collaboration

2. The ALPHA Refresher Initial goal: trapped antihydrogen
Transverse multipole for trapping antihydrogen
Higher order (octupole) to minimize plasma perturbations
Longitudinal trapping by mirror coils
Well depth of about 1 K at r=23 mm
Silicon vertex detector, no 511 keV gamma detector
Special magnet construction to minimize scattering of pions
Three layers of silicon - reconstruct track curvature
ATHENA positron source - new 75 mCi source
All lasers from ATHENA

3. Apparatus Cross Section

4. External Solenoid

5. Axial Field Configuration
3 T in catching region, 1 T in mixing for
larger neutral well depth
Outer solenoid
Inner solenoid
Mirror coils

6. Trap Magnet Prototype
Magnet exceeds design goals, proceeding with final version (8 layers, 2 mirrors, inner solenoid), article in preparation
Initial tests with electrons
Open now for modification
Continue plasma studies until May
Two layer multipole plus one mirror coil
Installed in 8 T solenoid at Berkeley
Internal Penning trap for electrons
Study magnet performance, quench protection, plasma behavior, etc.

7. Berkeley Set-up

8. TYPICAL QUENCH In brief Berkeley system:
Magnet very robust against quenching
Meets or exceeds magnetic design
First results with particles: straight-through, encouraging - agree with simulations
Clear superiority over quadrupole
First electrons trapped - no important results yet
Continue operation until May
Study trapping
Study magnetic coupling between coils
Gain important operating experience
Test thin-walled trap
The top graph shows to the voltage applied to the heater.
The second graph shows the current through the octupole.
The third graph shows the resistivity of the heater segment, and the fourth shows the temperature of this segment.
The fifth graph shows the potential across the heater segment and the two nearest segments, while the last graph zooms in on the times just after the quench.
The geometry is shown in the schematic. We calculate the quench velocity by measuring the time the quench takes to cross the “propagation” segment; namely, the time between when the quench first appears in propagation segment, and when it first appears in the “detection” segment. The quench velocity is this time divided into 2.0cm; in this case, about 29m/s.

9. Final Magnet Fabrication I

10. Final Magnet Fabrication II

11. Trap Electrode Configuration
quadrupole
Pbar direction
multipole s=6

12. Trap Electrode Design

13. Detector Conceptual Drawing
3 layers
8, 10, 12 azimuthal segments
Split axially into two half-detectors
Basic sensor 60x115 mm, 300 m thick
Two sensors butted axially per “ladder”
Total length 460 mm
0.234 mm pitch in r- (256 channels/ladder)
0.898 mm pitch in z (256 channels/ladder)
4 readout chips per ladder - IDEAS VA1TA with self-trigger
Carbon fiber support structure

14. Sensor Schematic
256 horizontal strips
on front
Not to scale

15. Vertex Resolution

16. Monte Carlo Simulations
Annihilations on Penning trap wall
Uniform distribution
“Hot spots”

17. Detector DAQ Schematic
128 ch x 4 x 60  ch
6 ADC modules VF48
1 ADC for 1 layer half-detector
14 repeater cards
No analog multiplexing 
less dead time for Trigger

18. ALPHA Status and Milestones
Design of apparatus complete, critical components being fabricated
Active theory involvement in all aspects of experiment
Active parallel, prototype program at Berkeley for SC magnets and trap physics
Final magnets being produced at BNL, ready for June start-up
New trap construction techniques developed, control system
Si vertex detector delayed by funding considerations, now fully funded
Start up with 1/2 detector axial length and reduced azimuthal coverage
Continue detector fabrication during the run, install 2nd half when complete
Approved 2006 physics goals achievable with scintillators and field ionization
Experiment fully funded; two successful peer review grants (UK, Canada) in 2005

19. ALPHA RUN PLAN/ BEAM REQUEST
SCINTILLATORS
SCINTILLATORS
NEW MCP DETECTOR
SCINTILLATORS
SCINTILLATORS,
SILICON
NEW!
NEW!
SCINTILLATORS and
Field ionization, or
SILICON
NEW!
NEW!
NEW!

20. Longer Term

21. “SELENA” Comparable to existing Liquid helium Capacity in experiments
Use BNL technique to make SC
Combined-function magnets, electron
cooler and compensation solenoids
Cold bore vacuum system: lifetime problem at low energy solved
No iron in construction: hysteresis concerns for repeated deceleration eliminated
FYI: ALPHA prototype $20,000
Comparable to existing Liquid helium
Capacity in experiments

22. People University of Aarhus: P.D. Bowe, J.S. Hangst
Auburn University; F. Robicheaux
University of Calgary: R.I. Thompson
University of California, Berkeley: A. Deutsch, K. Gomberoff, W. Bertsche, E. Sarid†, J. Wurtele, J. Fajans
University of Liverpool: A. Boston, M. Chartier, R.D. Page, P. Nolan
University of Manitoba: G. Gwinner
RIKEN: Y. Yamazaki
Federal University of Rio de Janeiro: D. Miranda, C. Cesar
University of Tokyo: R. Funakoshi, L.G.C. Posada, R. Hayano
TRIUMF: J. Dilling, K. Ochanski, D. Gill, A. Olin, L. Kurchaninov, M.C. Fujiwara
University of Wales, Swansea: M. Jenkins, L.V. Jørgensen, N. Madsen, H.H. Telle, D.P. van der Werf, M. Charlton
† Permanent address: Physics Department, NRCN, Beer-Sheva, Israel