Gabrielse 2006

Setting a Trap for

Gerald Gabrielse, ATRAP Spokesperson (CERN) Leverett Professor of , Harvard

Science and science fiction

Warning: This Talk is Not About Science Fiction. Gabrielse Setting a Trap for Antimatter

Support from NSF, AFOSR

Matter and Antimatter? Particle and Atoms of Matter and Antimatter Annihilation Challenges Traps: Containers Without Walls Making Antimatter Atoms? Why Should We Do This? Gabrielse Where Did You Learn About Antimatter?

Dr. Spock “knew”

Antimatter annihilation Æ powered Star Trek space ship “Enterprise” “going boldly where no one had gone before” Gabrielse Generations of Trekies

hardware: android software: hologram

We study antimatter. How close are we to the Star Trek imagination? Gabrielse The Science Reality Behind the Science Fiction Imagination

What is Matter?

What is Antimatter? Gabrielse We Are Made of Matter Gabrielse Particles of Matter and Antimatter: Opposite and Identical charge mass

Only measurements tell how identical Gabrielse Matter and Antimatter Atoms

uncharged uncharged atom anti-atom

Particle and antiparticle charges are opposite Both atoms are uncharged Æ same charge Gabrielse Gabrielse

According to Physics as We Understand It Æ Looks Like the Whole Universe Could Have Been Made of Antimatter

How would an antimatter universe be different?

Why is our universe made of matter rather than antimatter? Gabrielse What Would I Look Like If I Were Made of Antimatter?

• Æ • neutrons Æ antineutrons • Æ anti-electrons (positrons) ? Less mass?

Handsome?

More intelligent? Gabrielse What Would I Look Like If I Were Made of Antimatter? • protons Æ antiprotons • neutron Æ antineutrons • electrons Æ anti-electrons (positrons)

Antimatter Gabrielse

Big disappointment: • Antimatter Gabrielse looks the same! • Antimatter Gabrielse has the same mass! • Antimatter Gabrielse has the same limited brain power! Gabrielse Universe Made of Antimatter

• Essentially the same as a universe made of matter

• We only know two ways for inhabitants to know whether they live in a universe made of matter or antimatter (Need a large accelerator complex and sophisticated techniques)

Why is our universe made of matter?

(seems like antimatter would work just as well) Gabrielse Gabrielse

Why Are Science Fiction Writers so Fascinated? Antimatter and Matter Particles Gabrielse Annihilate Each Other Gabrielse What Happens When Antimatter and Matter Gabrielse Meet?

Anti-Gabrielse Gabrielse

About to shake hands Gabrielse Huge Energy Release!

100 kg 100 kg Anti-Gabrielse Gabrielse

energy mass that 200 kg released disappears E = mc2 Einstein’s famous formula

5,000,000,000,000 kilowatt-hours Yearly output of 500 nuclear power plants Energy from 4200 Megatons of TNT Gabrielse Energy Released Efficiency = Mass of Fuel Used

Annihilation 100 % Nuclear fission 0.1 % Nuclear fusion 0.1 % (or a bit higher) Chemical fuel 0.000 000 3 %

Annihilation • 1000 times more bang for the gram compared to nuclear fuel

Energy Source of the Future? No, certainly not Antimatter Weapons? No, certainly not Antimatter Rockets? Doubtful, … maybe in distant future Gabrielse Trapping and Annihilation Makes its Way Into Popular Culture

Star Trek – antimatter powers the space ship Enterprise

Serious Play: Hapgood Fiction best seller Author: Tom Stoppard Gabrielse Should the Pope Have Worried?

Missing detail: if all the antiprotons we have made in the history of the world were annihilated at the same time

Æ Not enough energy to boil a pot of tea

Clearly the pope should have studied more science Gabrielse Gabrielse Embarrassing, Unsolved Mystery: How did our Matter Universe Survive Cooling After the Big Bang?

Big bang Æ equal amounts of matter and antimatter created during hot time As universe cools Æ antimatter and matter annihilate

Big Questions: • How did any matter survive? • How is it that we exist? Our experiments are looking for evidence of any way that antiparticles and particles may differ Gabrielse Our “Explanations” are Not so Satisfactory (My opinion)

Baryon-Antibaryon Asymmetry in Universe is Not Understood Standard Explanation Alternate • CP violation • CPT violation • Violation of baryon number • Violation of baryon number • Thermodynamic non-equilibrium • Thermo. equilib. Bertolami, Colladay, Kostelecky, Potting Phys. Lett. B 395, 178 (1997)

Why did a universe made of matter survive the big bang? Makes sense look for answers to such fundamental questions in the few places that we can hope to do so very precisely.

Bigger problem: don’t understand dark energy within 120 orders of magnitude Gabrielse Gabrielse

Low Energy Studies of Antimatter

CERN Laboratory (Geneva) makes it

We slow it, catch it, cool it, study it Start Need a container without walls to avoid annihilation here

trap Gabrielse Particle Trap – A “Container Without Walls”

Need two truths to understand particle trap 1. Charged particles go in circles near a magnet 2. Same sign charges repel

Horseshoe Magnet ---

negative antiproton --- Gabrielse ATRAP – Trap and Detectors Small View

fibers positron 77 K source

positron traps 5.3 Tesla magnetic field rotating electrode antiprotons 4.2 K antiproton traps BGO Harvard: Trap, vacuum, rf electronics 77 K Juelich: Scintillation detectors Garching, York, Mainz: Lasers Gabrielse (Harvard)

Rotating • 4 K, 6 Tesla • electrode • single crystal • field emission point

1 cm Approx. (Photo by P. Horowitz) 100 leads Gabrielse Gabrielse One Charged Particle in a Trap

One Æ more than 10 months One antiproton Æ several months

Can study the particle properties with extremely high precision

Antiproton and have the same charge-to-mass ratio to better than 1 part in 1010 = 10000000000 Measure the electron magnetic moment to better than 1 part in 1012 = 1000000000000 Æ Gives a new value for the fine structure constant α that is much more accurate Gabrielse So far, the most stringent CPT test with baryons comes from One-Antiproton Radio

Antenna FM Radio

Tuning Speaker

“volume”

frequency tuning Gabrielse Special Relativity Is Crucial Å year of Einstein Plan: Compare cyclotron frequency for antiproton and proton Æ compares Q/M for antiproton and proton (if B stays same) Æ test of CPT invariance for baryon/antibaryon system

Problem: Antiproton cyclotron frequency shifts in time Highly non-relativistic antiproton

Q K ω = B γ =+1 2 c M Mc 1eV =+1 1GeV =1.000000001 Actually, highly “relativistic” at 1 eV Å due to high resolution Q ω = B c M Extrapolate Einstein away γ K Æ 0 eV Gabrielse Polarization Effect Discovered with Molecular Ions J.K. Thompson, S. Rainville and D.E. Pritchard, Nature Lett. 430, 58 (2004)

Motional radial electric field: E = vB Æ polarizes the ion radially: d = αE= -αvB Ion experiences • magnetic force on its charge: -evB • additional force on it dipole moment: -dωΒ The additional polarization force could be expected to vanish as we take the vÆ0 limit in our experiment 2 But, it does not. Instead ∆ωc B =−α =70 ppt ωc M

not really statistically significant (an excuse to measure more accurately?) corrected TRAP Improved the Comparison of AntiprotonGabrielse 6 qm/ (antiproton) and Proton by ~10 =−0.99999999991(9) Bevatron (p discovery) qm/(a) (proton) (b) 910×=2 −11 90ppt best CPT test with baryons 10 -1 (exotic 10 -2 atoms) 10 -3 CERN Trap II 10 -4 1 10 -5 BNL -6

10 ppb 10 -7 TRAP I 5 -8 610×

fractional accuracy fractional 10 10 -9 0 10 -10 TRAP II TRAP III 1960 1970 1980 1990 2000 year TRAP III

100 antiprotons and protons G. Gabrielse, A. Khabbaz, D.S. Hall, C. Heimann, H. Kalinowsky, W. Jhe; Phys. Rev. Lett. 82, 3198 (1999). Gabrielse Last TRAP Measurement of Antiproton Q/M

improved Low Energy Antiproton Ring apparatus (LEAR) shut down and technique

Could do significantly better! Q/M much more accurate than Q and M separately Gabrielse

Given that q/m magnitudes are the same, could q and m change to keep q/m constant?

TRAP: Directly compare q/m for antiproton and proton ASACUSA: Indirect measure of q2m for antiproton

- antiprotonic He spectroscopy - and detailed structure calculations - measured Rydberg constant, etc.

Comparisons of Antiproton and Proton TRAP: q/m same to fractional accuracy 0.000 000 000 09 ASACUSA: q2m same to fractional accuracy 0.000 000 06 Together: q and m same to fractional accuracy 0.000 000 06

q/m comparison is 700 times more accurate Gabrielse Gabrielse Digression: Quantum Limit of a Particle in a Trap

ψ 2 One Electron Quantum Cyclotron

0.1 µm

Student award symposium: Brian Odom, Thursday, 2 pm Gabrielse Quantum Cyclotron

one electron Æ quantum average quantum number < 1, etc. Æ quantum

υ c ≈ 150 GHz

n = 4 n = 3 n = 2 n = 1 ωc = 7.2 kelvin B ≈ 6 Tesla n = 0

To realize a quantum cyclotron: • need cyclotron temperature << 7.2 kelvin • need sensitivity to detect a one quantum excitation Gabrielse Cylindrical Penning Trap

Electrostatic quadrupole potential Æ good enough near trap center Gabrielse Quantum Jumps as a Function of Temperature • one electron • Fock states of a cyclotron oscillators • due to blackbody photons

0.23

0.11

0.03

9 x 10-39 average number On a short time scale of blackbody Æ in one Fock state or another photons in the Averaged over hours cavity Æ in a thermal state Gabrielse Quantum Jump Spectroscopy

• lowest cyclotron and spin states • one electron in a Penning trap Gabrielse A New Measurement of the Electron Magnetic Moment magnetic S spin µµ= g moment B Bohr magneton e 2m g / 2= 1.001159 652 180 85 ±×0.000 000 000 000 76 7.6 10−13

• First improved measurement since 1987 • Nearly six times improved accuracy • Likely more accuracy coming Gabrielse New Determination of the Fine Structure Constant

1 e2 • Strength of the electromagnetic interaction α = • Important component of our system of fundamental constants 4 0 c πε α −1 =137.035 999 710 ±×0.000 000 096 7.0 10−10

• First improved measurement since 1987 • Ten times more accurate than atom-recoil methods • Component of new mass standard Gabrielse

Digression to Illustrate Quantum Limit of One Particle in a Trap

is over Gabrielse Gabrielse Offers a More Stringent Probe than Q/M of Antiproton and Proton

Old Long Term Goal New Long Term Goal CPT Test CPT Test by comparing by comparing Q/M of Æ laser spectroscopy of antiproton and proton antihydrogen and hydrogen

9 x 10-11 much more accurate Gabrielse Motivations and Goals

Clear, Stable, Long Term Highly accurate spectroscopic comparisons of antihydrogen atoms and hydrogen atoms Æ Extremely accurate CPT tests Æ Gravitational studies

• Clear before the AD was built • Clear while the AD rested for 1.5 years • Clear now • Clear in the future Gabrielse Comparing the CPT Tests Warning – without CPT violation models it is hard to compare CPT Test Measurement Free Accuracy Accuracy Gift _ -18 -3 15 K0 K0 2 x 10 2 x 10 10 Mesons

e+ e- 2 x 10-12 2 x 10-9 103 Leptons improve with _ antihydrogen

P P 9 x 10-11 9 x 10-11 1

baryons 3 fundamentally different types of particles 3 fundamentally Gabrielse Seek to Improve Lepton and Baryon CPT Tests

ATRAP members

++2 2 − R∞[H]me[] qe []q[]p 1+ me [] / Mp [] = −+−  R∞[H] me[] qe []qp[ ][1+ m [e ]/ M p] Gabrielse Why Cold Antihydrogen?

Goal: Highly Accurate Comparison – Antihydrogen and Hydrogen

No Hope with Hot Antihydrogen 1995 – CERN • too fast v ~ c 1997 -- Fermilab • little measurement time • too few atoms Gabrielse Hydrogen 1s – 2s Spectroscopy

(Haensch, et al., Max Planck Soc., Garching) http://www.mpq.mpg.de/~haensch/hydrogen/h.html

Many fewer antihydrogen atoms will likely be available Gabrielse Not as Accurate Yet, but Similar Environment

Still uses a lot more hydrogen atoms than we expect to have antihydrogen atoms Gabrielse Spectroscopy on 1000 or Fewer Atoms Seems Possible Æ 1 part in 1012 estimated

T. Haensch and C. Zimmerman, Laser Spectroscopy of Hydrogen and Antihydrogen, Hyper. Int. 76, 47 (1993). Gabrielse Gravity and Antihydrogen Gabrielse Gabrielse Accumulating Many Antiprotons in a Trap

Basic Ideas and Techniques Developed by Our TRAP Collaboration at CERN’s LEAR: 1986 - 2000)

• Slow antiprotons in matter • Capture antiprotons in flight • Electron cooling Æ 4.2 K • 5 x 10-17 Torr

Used by 3 collaborations at the CERN AD ATRAP, ATHENA and ASACUSA Gabrielse We Go to CERN

skiing

France

Switzerland (Geneva)

Makes matter and antimatter particles Gabrielse ATRAP Prof. G. Gabrielse Dr. T. Roach J. Estrada A. Speck (Spokesperson) Dr. J.N. Tan P. Yesley D. Lesage Dr. C. Storry P. Oxley P. Larochelle Dr. J. Tan N. Bowden Dr. B. Levitt M. Wessels Juelich Laboratory Dr. W. Oelert Dr. T. Sefzick Z. Zhang Dr. G. Schepers Dr. D. Grzonka Max Planck Institute for Quantum Optics Prof. T. Haensch Dr. J. Walz H. Pittner M. Herrmann York University Prof. E. Hessels D. Comeau Prof. C. Storry University of Mainz Prof. J. Walz Earlier contributions from Bonn and Vienna For a low energy, laboratory physicist Gabrielse going to a particle physics lab was an adventure

1981 ventured to Fermilab as a postdoc Æ only one person was interested “Tev or bust”

1986 go to CERN (still essentially a postdoc) Æ get thrown out of first office Æ get 24 hours of antiproton beam to demonstrate slowing Æ get 24 hours to demonstrate trapping

Amazingly, this worked Æ CERN extended more hospitality (postdoc Æ professor)

Continuing challenge: the way that we must invent our way through our experiments is very different from the highly scheduled modern particle experiments Æ still not well understood by committees, etc. Gabrielse Antiproton Capture – the Movie

p p r position

z position

p

p Axial Energy

z position

"First Capture of Antiprotons in a Penning Trap: A KeV Source", G. Gabrielse, X. Fei, K. Helmerson, S.L. Rolston, R. Tjoelker, T.A. Trainor, H. Kalinowsky, J. Haas, and W. Kells; Phys. Rev. Lett. 57, 2504 (1986). Gabrielse Electron-Cooling of Antiprotons – in a Trap • Antiprotons cool via collisions with electrons • Electrons radiate away excess energy

p

p Axial Energy

e-

z position

"Cooling and Slowing of Trapped Antiprotons Below 100 meV", G. Gabrielse, X. Fei, L.A. Orozco, R. Tjoelker, J. Haas, H. Kalinowsky, T.A. Trainor, W. Kells; Phys. Rev. Lett. 63, 1360 (1989). Gabrielse Antiproton Years: TRAP at CERN’s LEAR

1981 – 1985 Proposals 1990 First antiproton stacking in - Fermilab trap -CERN 1990 q/m of antiproton and proton 1986 Slow antiprotons in matter same to 4 x 10-8 21 MeV Æ 3 keV 1992 First observation of one 1986 First trapping of antiprotons trapped antiproton < 300 < 3 keV ~10 minutes 1995 q/m of antiproton and proton 1989 Hold 105 antiprotons for 2 months same to 1 x 10-9 lifetime > 3.4 months pressure < 5 x 10-17 Torr 1999 q/m of antiproton and proton same to 9 x 10-11 1989 First electron cooling in trap 106-fold improvement over 3 keV Æ 0.3 meV (4.2 K) all other techniques

antiprotons First antiproton trap Gabrielse Key TRAP Publications

• Phys. Rev. Lett. 57, 2504 (1986). First trapping of antiprotons • Phys. Lett. A 129, 38 (1988) • Phys. Rev. Lett. 63, 1360 (1989). • Phys. Rev. A (Rapid Comm.) 40, 481 (1989). • Phys. Rev. Lett. 65, 1317 (1990). • Sci. Am., Dec. , pp. 78 – 89 (1992). • Phys. Rev. Lett. 75, 806 (1995). • Phys. Rev. Lett. 74, 3544 (1995). • Phys. Rev. Lett. 77, 806 (1996). • Phys. Rev. Lett. 82, 3198 (1999). • Phys. Lett. B 455, 311 (1999). • Phys. Rev. Lett. (14 Feb. 2000). 4.2 K antiprotons and positrons interacting (preparing for antihydrogen) Gabrielse LEAR – Low Energy Antiproton Ring (at CERN)

Built to slowly spill antiprotons Æ meson spectroscopy and CP studies

we persuaded CERN to give us antiproton pulses instead Gabrielse LEAR – Low Energy Antiproton Ring

AC – catch antiprotons AA – stack antiprotons, cool LEAR – decelerate antiprotons

ÆWe got 109 antiprotons in a pulse every 5 minutes (maximum, need refill time) Gabrielse CERN – the Largest and Smallest Accelerators

2 2Mp c LEAR and AD

1010

TRAP 4.2 K 0.3 meV

70 mK, lowest storage energy for any charged particles “Stacking” Gabrielse Accumulating Antiprotons – just a matter of time

Can stack this number in a single well, for more need multiple wells

ATRAP’s good vacuum < 5 x 10-17 Torr allows such stacking (ATHENA and ASACUSA use stacking but with less bunches)

First Demonstration – Antiprotons Stacked in a Trap G. Gabrielse, X. Fei, L.A. Orozco, R. Tjoelker, J. Haas, H. Kalinowsky, T.A. Trainor, W. Kells Phys. Rev. Lett. 63, 1360 (1989) “Stacking of Cold Antiprotons” ATRAP Phys. Lett. B 548, 140 (2002) Gabrielse Gabrielse Making Atoms Entirely of Antimatter

Antihydrogen atoms 4.2 K Gabrielse Cold Antihydrogen Aspirations Announced Long Ago Goals • Produce cold antihydrogen • Trap cold antihydrogen • Use accurate laser spectroscopy to compare antihydrogen and hydrogen “For me, the most attractive way ... would be to capture the antihydrogen in a neutral particle trap ... The objective would be to then study the properties of a small number of [antihydrogen] atoms confined in the neutral trap for a long time.”

Gerald Gabrielse, 1986 Erice Lecture (shortly after first pbar trapping) In Fundamental Symmetries, (P.Bloch, P. Paulopoulos, and R. Klapisch, Eds.) p. 59, Plenum, New York (1987). Gabrielse Meanwhile: Very Fast Antihydrogen Atoms Æ First at CERN in Geneva, Switzerland

"Production of Antihydrogen" G.Baur et al. (team led by W. Oelert) Phys.Lett. B 368 (1996) 251-258. Æ Then at Fermilab in the USA

"Observation of Antihydrogen" G. Blanford, et al. Phys. Rev. Lett. 80, 3037 (1998).

Demonstrated the existence of antihydrogen atoms.

too few atoms cannot make accurate comparisons atoms go too fast of antihydrogen and hydrogen

Æ Need slow antihydrogen for precise study Gabrielse Now: Two Ways to Produce Slow Antihydrogen

1. In a nested Penning trap, during positron cooling of antiprotons Device and technique – TRAP and ATRAP (1986 – 2001) Used to produce slow antihydrogen – ATHENA and ATRAP (2002)

2. Laser-controlled resonant charge exchange Developed the technique – Harvard and York (2001-2003) ATRAP (2004) Only a few atoms made so far – proof-of-principle

Two Ways That Do Not (Yet) Produce Slow Antihydrogen 1. Field-assisted formation – ATRAP (2002)

2. Laser stimulated formation with CO2 laser – ATHENA (2004) Method 1: Nested Penning Trap Gabrielse 3-Body “Recombination”

Nested Penning Trap 3-Body “Recombination” Method 1: Positron Cooling of AntiprotonsGabrielse in a Nested Penning Trap p

e+

TRAP/ATRAP Develops the Nested Penning Trap Proposed nested trap as a way to make antihydrogen "Antihydrogen Production Using Trapped Plasmas" G. Gabrielse, L. Haarsma, S. Rolston and W. Kells Physics Letters A 129, 38 (1988) "Electron-Cooling of Protons in a Nested Penning Trap" D.S. Hall, G. Gabrielse Phys. Rev. Lett. 77, 1962 (1996) "First Positron Cooling of Antiprotons" Cold antihydrogen was ATRAP Phys. Lett. B 507, 1 (2001) made in 2001 Æ not cleanly detected Gabrielse One Production Method – Two Detection Techniques

2001: ATRAP, "First Positron Cooling of Antiprotons" Phys. Lett. B 507, 1 (2001) Crucial Device: Nested Penning Trap Crucial Technique: Positron Cooling of Antiprotons Cold trapped positrons cool antiprotons to a low relative velocity with the positrons Æ produces slow antihydrogen

2002: ATHENA and ATRAP demonstrated that antihydrogen was produced by this device and technique ATHENA, Nature 419, 456 (2002) same production ATRAP, Phys. Rev. Lett. 89, 213401 (2002) ATRAP, Phys. Rev. Lett. 89, 233401 (2002) different detection Gabrielse Comparing the Two Detection Methods Athena – detects positron and antiproton annihilations within 5 microseconds and +/- 8 mm of each other (now using mostly antiproton annihilations, 4 mm resolution) Good: Detects antihydrogen whatever is velocity and state Not as good: Insensitive to antihydrogen velocity and state

ATRAP – field ionization detection Good: No background Probes internal state of the antihydrogen Can measure antihydrogen velocity Not as good: Can only detect states that can be field ionized (Hope to use lasers to excite lower states to states that can be field ionized) Gabrielse ATRAP’s Field Ionization Method • Use Field-Ionization – strip positron and store antiproton

p

p e+ H e+

• Dump stripping well after experiment – Dump other particles before looking in stripping well – Ramp quickly compared to cosmic background count rate (ramp in 20ms, get one cosmic/second) – Essentially no background for this measurement! Gabrielse Only Detect Ionized Antihydrogen • Field-Ionization is very robust – only antihydrogen can get antiprotons into the stripping well p

p

e+

• Antiprotons knocked out of well leave to the left

• Even if an antiproton has enough energy to get to the ionization well, it can not get into the well Gabrielse Driven Antihydrogen Production Æ Higher Rate • Recall that antiprotons cool below the positrons – interaction stops • Drive axial motion of antiprotons repeatedly to “drive” interaction

e+ p

• Antihydrogen production rate is increased by more than an order of magnitude using this method Gabrielse No Useful Antihydrogen Yet, But We Have Methods to Measure and Optimize

How close to the ground state? ATRAP’s field ionization method is only probe so far

How cold? Vary ionization field F in time to find out. F ~ Cos(ωt) • Fast atoms make it through while field is at a low value. • Slow atoms never avoid ionization Gabrielse Observed Antihydrogen Atoms are Very Weakly Bound

Breakdown of the GCA picture Æ chaotic motion? Gabrielse Simulation of Field Ionization Spectrum T. Pohl, H. R. Sadeghpour and G. Gabrielse Talk here: Pohl GCA, before charge exchange

GCA, after charge exchange

ATRAP Measurement

GCA Full simulation Gabrielse First Measurement of an Antihydrogen Velocity

v ∼ 20 vthermal

200 meV

• This is for the most weakly bound antihydrogen states • More deeply bound states may be going more slowly

ATRAP, "First Measurement of the Velocity of Slow Antihydrogen Atoms", Phys. Rev. Lett. 93, 073401 (2004). Gabrielse More Favorable Interpretation Charge exchange of antihydrogen with faster protons

T. Pohl, H. R. Sadeghpour and G. Gabrielse Talk here: Pohl Gabrielse

Great Features of Method I • High antihydrogen production rate • Easy and robust

Not-so-Great (so Far) • Highly excited antihydrogen is produced • Detected antihydrogen has velocity much higher average for 4.2 K (big mystery!) • Variations from production attempt to production attempt is larger than we understand (something not under control)

Conclusion: Need larger trap and more positrons Æ More collisional deexcitation Æ More collisional cooling Æ More stability in the production process (away from trap walls) Gabrielse Very Different Method II to Produce Slow Antihydrogen

First Laser-Controlled Antihydrogen Production Use positronium – Deutch, … Use Rydberg positronium – Charlton, … Use charge exchange to produce the positronium – Hessels, …

Calculation (no B field): E.A. Hessels, D.M. Homan, M.J. Cavagnero, Phys. Rev. A 57, 1668 (1998).

Observe Rydberg Cs and Rydberg Positronium (at Harvard)

Observe Antihydrogen n~37 (at CERN) Æ State-selected antihydrogen, should be very cold Æ hope to de-excite with a laser (not easy) or collisions Gabrielse Antihydrogen Via Laser-Controlled Resonant Charge Exchange

852 nm

510.6 nm Gabrielse

Great Features of Method II • Lasers control the state of the antihydrogen produced • Likely the first truly cold antihydrogen

Not-so-Great (so Far) • Highly excited antihydrogen is produced • Detection rate is very low (production rate is much better)

Conclusion: Need larger trap and more positrons Æ More detectable antihydrogen to work with Gabrielse Current “Do or Die” Challenges (no change since Villars) 1. Deexcite the highly excited antihydrogen that is produced. 2. Need slower antihydrogen produced (in method I) 3. Add field gradients of a magnet trap for antihydrogen without destroying the antihydrogen production rate

We believe that a solution requires Æ Larger traps with more positrons and antiprotons Æ Room for magnetic gradient traps Æ Room for laser access Gabrielse Gabrielse ATRAP II – Completely New

What to do when CERN shuts us down for a year and one half, and delivers less antiproton beam during the first year back? Æ Build a completely new apparatus based upon what we have learned at the AD

Much Bigger Æ room for bigger trap, more particles, more cooling Æ room for magnetic trap Æ room for more laser access Æ room for annihilation imaging New Beam Steering, New Soleniod, New Dewars, New Detectors, New Electronics, New Positron Source, …

Will we be ready? Æ We still hope so, but this will be a very busy beam run. ATRAP 2006 Gabrielse Harvard University Prof. G. Gabrielse Dr. B. Levitt D. Le Sage (Spokesperson) Dr. I. Kuljanishvili P. Larochelle Dr. J. Wrubel W. Kolthamme Juelich Laboratory Dr. W. Oelert Dr. D. Grzonka Z. Zhang Dr. F. Goldenbaum Dr. T. Sefzick York University Prof. E. Hessels M. George D. Comeau Prof. C. Storry M. Weel A. Carew University of Mainz Prof.. J. Walz F. Markert Rowland Institute at Harvard Dr. A. Speck Free Univesity of Amsterdam Prof. E. Eikema Max Planck Institute for Quantum Optics Prof. T. Haensch Gabrielse Comparing ATRAP I to ATRAP II Gabrielse

Some ATRAP Members at a Recent Meeting Harvard, 13 January 2006

Missing: Some ATRAP members from Juelich, Rowland, Mainz, Amsterdam Gabrielse Different Configurations Envisioned for ATRAP II Gabrielse Connection to the AD

ATRAP II Solenoid

AD antiprotons

AD Team is correcting for the fringing field Gabrielse Location of Positron Source for ATRAP II

ATRAP II Solenoid ATRAP I low energy and Traps low flux positron guide

positron source (locally shielded)

rear entrance A new sodium source should could be a fence, if this is more arrive soon. convenient than concrete Will it??? Gabrielse Coming Gabrielse A Trap for Antimatter Atoms

Atom with a properly alligned magnetic moment will be trapped in a minimum of magnetic field Gabrielse Conclusions Gabrielse Where We Are, and Where We are Going

A lot has been accomplished • We can regularly cool antimatter particles to extremely low energies • We can readily make many antihydrogen atoms

Much remains to be done • Need to make antihydrogen atoms in their ground state • Need to slow the antihydrogen atoms even more to trap them (some may be cold enough)

Goal • Use lasers to probe for any tiny differences between atoms of antimatter and matter Gabrielse Why Study Antimatter? Solve energy shortage problem, make weapons, make rockets

Look closely for any tiny differences between antimatter and matter • Test basic theories that suggest that matter and antimatter are opposite in charge, but identical in mass, … • Probing reality at its most fundamental level

Such fundamental experiments typically lead to new technologies e.g. Transistor, Laser, World Wide Web (CERN) e.g. From our experiments so far • new cell designs for ion cyclotron resonance imaging of pharmaceuticals • self-shielding solenoid used for NMR and MRI imaging • first continuous Lyman alpha radiation Gabrielse If Antimatter Atoms Interest You Gabrielse Antihydrogen Review Paper

"Atoms Made Entirely of Antimatter: Two Methods Produce Slow Antihydrogen" G. Gabrielse Advances in Atomic, Molecular and Optical Physics 50 (2004).

Simpler Discussions “Extremely Cold Antiprotons" G. Gabrielse Scientific American 50 (1986)

“Making Cold Antimatter” G.P. Collins Scientific American (June, 2005)