Weak (and ridiculously weak) interactions as tests of fundamental physics
Dan Melconian Cyclotron Institute/Dept. of Physics & Astronomy Texas A&M University Presentation for REUs — July 25, 2012 Overview
1. Fundamental symmetries ● what is our current understanding? ● what lies beyond?
2. Tools of the trade ● trapping short-lived neutral atoms ● polarizing the atom cloud
3. Angular correlations using laser-cooled atoms ● angular correlations of polarized 37K ● expected limits on right-handed currents
July 25, 2012 Dan Melconian –2 REU presentation Scope of fundamental physics
nucleons u u d u d d d u quarks u d d u
e−
the atom from the very smallest scales . . .
July 25, 2012 Dan Melconian –3 REU presentation Scope of fundamental physics
nucleons u u d u d GeV d −13 d u 2x10 quarks −12 u d d 10 u 3x10−10 10−4 e− 10−1 102
1015 the atom 1019 from the very smallest scales . . .
10−44 10−37 s 10−10 s 10−5 s 102 s 3x105 y 109 y 9 12x10 y . . . to the very largest July 25, 2012 Dan Melconian –3 REU presentation The Standard Model
All of the known elementary particles and their interactions are described within the framework of
July 25, 2012 Dan Melconian –4 REU presentation The Standard Model
All of the known elementary particles and their interactions are described within the framework of
● quantum + special rel ⇒ quantum field theory
July 25, 2012 Dan Melconian –4 REU presentation The Standard Model
All of the known elementary particles and their interactions are described within the framework of
● quantum + special rel ⇒ quantum field theory ● Noether’s theorem: symmetry ⇔ conservation law
July 25, 2012 Dan Melconian –4 REU presentation The Standard Model
All of the known elementary particles and their interactions are described within the framework of
● quantum + special rel ⇒ quantum field theory ● Noether’s theorem: symmetry ⇔ conservation law
Maxwell’s eqns invariant under conservation of ⇔ changes in vector potential electric charge, q
July 25, 2012 Dan Melconian –4 REU presentation The Standard Model
All of the known elementary particles and their interactions are described within the framework of
● quantum + special rel ⇒ quantum field theory ● Noether’s theorem: symmetry ⇔ conservation law
Maxwell’s eqns invariant under conservation of ⇔ changes in vector potential electric charge, q and there’s other symmetries too: time ⇔ energy space ⇔ momentum rotations ⇔ angular momentum . .
July 25, 2012 Dan Melconian –4 REU presentation The Standard Model
All of the known elementary particles and their interactions are described within the framework of
● quantum + special rel ⇒ quantum field theory ● Noether’s theorem: symmetry ⇔ conservation law electroweak
● SU(3) × SU(2)L × U(1) + (classical general rel)
strong z weak }| E&M{ gravity | {z } | {z } |{z} | {z }
July 25, 2012 Dan Melconian –4 REU presentation The Standard Model
All of the known elementary particles and their interactions are described within the framework of
● quantum + special rel ⇒ quantum field theory ● Noether’s theorem: symmetry ⇔ conservation law ● SU(3) × SU(2)L × U(1): strong + electroweak ● 12 elementary particles and 4 fundamental forces
1st 2nd 3rd Q mediator force ν ν ν 0 g strong leptons e µ τ e µ τ −1 W ± ◦ weak u c t +2/3 Z quarks d s b −1/3 γ EM
July 25, 2012 Dan Melconian –4 REU presentation That’s all fine and dandy, but. . . Does the Standard Model work??
July 25, 2012 Dan Melconian –5 REU presentation That’s all fine and dandy, but. . . Does the Standard Model work?? ± ● predicted the existence of the W , Z◦, g, c and t
July 25, 2012 Dan Melconian –5 REU presentation That’s all fine and dandy, but. . . Does the Standard Model work?? ± ● predicted the existence of the W , Z◦, g, c and t ● is a renormalizable theory
July 25, 2012 Dan Melconian –5 REU presentation That’s all fine and dandy, but. . . Does the Standard Model work?? ± ● predicted the existence of the W , Z◦, g, c and t ● is a renormalizable theory ● GSW ⇒ unified the weak force with electromagnetism
July 25, 2012 Dan Melconian –5 REU presentation That’s all fine and dandy, but. . . Does the Standard Model work?? ± ● predicted the existence of the W , Z◦, g, c and t ● is a renormalizable theory ● GSW ⇒ unified the weak force with electromagnetism ● QCD explains quark confinement
July 25, 2012 Dan Melconian –5 REU presentation That’s all fine and dandy, but. . . Does the Standard Model work?? ± ● predicted the existence of the W , Z◦, g, c and t ● is a renormalizable theory ● GSW ⇒ unified the weak force with electromagnetism ● QCD explains quark confinement 1 aµ ≡ 2(g − 2) −10 aµ(exp) = 11659208(6) × 10
11659000 −10 aµ(SM) = 11659181(8) × 10 − 10
10 ±1 part-per-million!! × µ
a (PRL 92 (2004) 161802)
July 25, 2012 Dan Melconian –5 REU presentation That’s all fine and dandy, but. . . Does the Standard Model work?? ± ● predicted the existence of the W , Z◦, g, c and t ● is a renormalizable theory ● GSW ⇒ unified the weak force with electromagnetism ● QCD explains quark confinement 1 aµ ≡ 2(g − 2) −10 aµ(exp) = 11659208(6) × 10
11659000 −10 aµ(SM) = 11659181(8) × 10 − 10
10 ±1 part-per-million!! × µ
a (PRL 92 (2004) 161802) Wow ...this is the most precisely tested theory ever conceived!
July 25, 2012 Dan Melconian –5 REU presentation But there are still questions . . .
● values of parameters: does our “ultimate” theory really need 25 arbi- trary constants? Do they change with time? ● dark matter: SM physics makes up only 4% of the energy-matter of the universe! ● baryon asymmetry: why more matter than anti-matter? ● strong CP : do axions exist? Fine-tuning? ● neutrinos: Dirac or Majorana? ● fermion generations: why three families? ● weak mixing: Is the CKM matrix unitary? ● parity violation: is parity maximally violated in the weak interaction? No right-handed currents? ● EW symmetry breaking: how do the fermions acquire mass? Mass hierarchy? ● gravity: of course can’t forget about a quantum description of gravity!
July 25, 2012 Dan Melconian –6 REU presentation Beyond the Standard Model
At our energy scales, we see four distinct forces . . .
July 25, 2012 Dan Melconian –7 REU presentation Beyond the Standard Model
But these coupling ‘constants’ aren’t really constant: αi → αi(Q)
→ electromagnetic and weak strengths equal at ≈ 1013 GeV
→ strong force gets weaker, but doesn’t unify with EW. . . .
July 25, 2012 Dan Melconian –7 REU presentation Beyond the Standard Model
But what if there is new physics we haven’t seen yet?
the running of the coupling constants would be affected; maybe they converge at some GUT scale? Are the three theories of E&M, weak and strong interactions all low-energy limits of one unifying theory?
July 25, 2012 Dan Melconian –7 REU presentation How do we test the SM?
colliders: CERN, SLAC, FNAL, BNL, KEK, DESY, .... direct search of particles
27 km
“go big or go home”
● large multi-national collabs ● billion $ price-tags
July 25, 2012 Dan Melconian –8 REU presentation How do we test the SM?
nuclear physics: radioactive ion beam facilities (ISOL/frag) indirect search via precision measurements
July 25, 2012 Dan Melconian –9 REU presentation How do we test the SM?
nuclear physics: radioactive ion beam facilities (ISOL/frag) indirect search via precision measurements
July 25, 2012 Dan Melconian –9 REU presentation How do we test the SM?
nuclear physics: radioactive ion beam facilities (ISOL/frag) indirect search via precision measurements
● smaller collaborations ● contribute to all aspects ● “table-top” physics
July 25, 2012 Dan Melconian –9 REU presentation How we all test the SM
● colliders: CERN, SLAC, FNAL, BNL, KEK, DESY ... ● nuclear physics: traps, exotic beams, neutron, EDMs, 0νββ,... ● cosmology & astrophysics: SN1987a, Big Bang nucleosynthesis, . . .
● muon decay: Michel parameters: ρ,δ,η, and ξ ● atomic physics: anapole moment, spectroscopy, . . .
all of these techniques are complementary and important ● different experiments probe different (new) physics ● if signal seen, cross-checks crucial!
often they are interdisciplinary (fun and a great basis for graduate students!)
July 25, 2012 Dan Melconian – 10 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
V =(x◦,y◦) PˆV = −V
(x◦,y◦)
(−x◦, −y◦)
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
A = M.C. Escher reptiles PˆA =+A
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
intrinsic parity ⇔ helicity or “handedness”
r × p → (−r) × (−p)= r × p (spin is an axial vector)
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
intrinsic parity ⇔ helicity or “handedness”
“Left-handed” “Right-handed”
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
intrinsic parity ⇔ helicity or “handedness” ● 1927: Wigner shows Maxwell’s equations conserve parity
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
intrinsic parity ⇔ helicity or “handedness” ● 1927: Wigner shows Maxwell’s equations conserve parity ● 1934: Fermi’s theory of β decay:
2 dW GF 2 2 ◦ = 5 peEe(Ee − A ) |Mfi| dEe (2π) ∗ Mfi = ψ Γi ψ, Γi =(S, P , V , A, T ) R
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
intrinsic parity ⇔ helicity or “handedness” ● 1927: Wigner shows Maxwell’s equations conserve parity ● 1934: Fermi’s theory of β decay: ● 1953: 6He, 19Ne decay suggested weak interaction is (S,T )
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
intrinsic parity ⇔ helicity or “handedness” ● 1927: Wigner shows Maxwell’s equations conserve parity ● 1934: Fermi’s theory of β decay: ● 1953: 6He, 19Ne decay suggested weak interaction is (S,T ) ● 1953: Dalitz points out the “θ − τ puzzle”: θ+ → π0π+ and τ + → π+π+π− (but same lifetime, mass, . . . )
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
intrinsic parity ⇔ helicity or “handedness” ● 1927: Wigner shows Maxwell’s equations conserve parity ● 1934: Fermi’s theory of β decay: ● 1953: 6He, 19Ne decay suggested weak interaction is (S,T ) ● 1953: Dalitz points out the “θ − τ puzzle”: θ+ → π0π+ and τ + → π+π+π− (but same lifetime, mass, . . . ) ● 1956: prompted Lee and Yang to question current convention . . . existing experiments do indicate parity conservation in strong and electromagnetic interactions, but that for weak interactions ...parity conservation is so far only an extrapolated hypothesis unsupported by experimental evidence. (Feynman bets parity is conserved) July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
intrinsic parity ⇔ helicity or “handedness” ● 1927: Wigner shows Maxwell’s equations conserve parity ● 1934: Fermi’s theory of β decay: ● 1953: 6He, 19Ne decay suggested weak interaction is (S,T ) ● 1953: Dalitz points out the “θ − τ puzzle”: K+ → π0π+ and K+ → π+π+π− (same particle; parity not conserved) ● 1956: prompted Lee and Yang to question current convention ● 1957: Wu (60Co), Garwin (µ+) favour (V −A) interaction
July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
intrinsic parity ⇔ helicity or “handedness” ● 1927: Wigner shows Maxwell’s equations conserve parity ● 1934: Fermi’s theory of β decay: ● 1953: 6He, 19Ne decay suggested weak interaction is (S,T ) ● 1953: Dalitz points out the “θ − τ puzzle”: K+ → π0π+ and K+ → π+π+π− (same particle; parity not conserved) ● 1956: prompted Lee and Yang to question current convention ● 1957: Wu (60Co), Garwin (µ+) favour (V −A) interaction
(Feynman loses $50) July 25, 2012 Dan Melconian – 11 REU presentation History up to 1957
● 1768: Kant debates nature of incongruent counterparts ● 1848: Pasteur observes optical rotation in chemical isomers ● 1924: Laporte introduces idea of parity conservation in q. m.
intrinsic parity ⇔ helicity or “handedness” ● 1927: Wigner shows Maxwell’s equations conserve parity ● 1934: Fermi’s theory of β decay: ● 1953: 6He, 19Ne decay suggested weak interaction is (S,T ) ● 1953: Dalitz points out the “θ − τ puzzle”: K+ → π0π+ and K+ → π+π+π− (same particle; parity not conserved) decay has a long history of developing our ● 1956: promptedβ Lee and Yang to question current convention understanding of fundamental symmetries ● 1957: Wu (60Co), Garwin (µ+) favour (V −A) interaction
July 25, 2012 Dan Melconian – 11 REU presentation The Standard Model (and beyond)
± ◦ The Electroweak Interaction: SU(2)L×U(1) ⇒ WL ,Z ,γ
Built upon maximal parity violation: Vector Pˆ|Ψ = −|Ψ
µ µ HSM = GF Vud e(γµ − γµγ5)νe u(γ − γ γ5)d
Axial − vector Pˆ|Ψ = +|Ψ
July 25, 2012 Dan Melconian – 12 REU presentation The Standard Model (and beyond)
± ◦ The Electroweak Interaction: SU(2)L×U(1) ⇒ WL ,Z ,γ
Built upon maximal parity violation: Vector Pˆ|Ψ = −|Ψ
µ µ HSM = GF Vud e(γµ − γµγ5)νe u(γ − γ γ5)d
Axial − vector Pˆ|Ψ = +|Ψ
low-energy limit of a deeper SU(2)R×SU(2)L×U(1) theory?
July 25, 2012 Dan Melconian – 12 REU presentation The Standard Model (and beyond)
± ◦ The Electroweak Interaction: SU(2)L×U(1) ⇒ WL ,Z ,γ
Built upon maximal parity violation: Vector Pˆ|Ψ = −|Ψ
µ µ HSM = GF Vud e(γµ − γµγ5)νe u(γ − γ γ5)d
Axial − vector Pˆ|Ψ = +|Ψ
low-energy limit of a deeper SU(2)R×SU(2)L×U(1) theory? ± ′ ⇒ 3 more vector bosons: WR ,Z Simplest extensions: “manifest left-right symmetric” models
only 2 new parameters: W2 mass and a mixing angle, ζ
|WL = cos ζ|W1 − sin ζ|W2
|WR = sin ζ|W1 + cos ζ|W2
July 25, 2012 Dan Melconian – 12 REU presentation RHCs would affect correlation parameters
−2ρ 3 ρ Aβ = 1+ρ2 5 − 5 q
−2ρ 3 ρ Bν = 1+ρ2 5 + 5 q
and Rslow =0
July 25, 2012 Dan Melconian – 13 REU presentation RHCs would affect correlation parameters In the presence of new physics, the angular distribution of β decay will be affected.
2 2 −2ρ 3 ρ −2ρ 3(1+x ) ρ(1−y ) Aβ = 1+ρ2 5 − 5 → 1+ρ2 (1−xy) 5(1+y2) − 5(1+y2) q h q i
2 2 −2ρ 3 ρ −2ρ 3(1+x ) ρ(1−y ) Bν = 1+ρ2 5 + 5 → 1+ρ2 (1−xy) 5(1+y2) + 5(1+y2) q h q i 2 and Rslow =0 → y
2 2 where x ≈ (ML/MR) − ζ and y ≈ (ML/MR) + ζ
are RHC parameters that are zero in the SM.
July 25, 2012 Dan Melconian – 13 REU presentation RHCs would affect correlation parameters In the presence of new physics, the angular distribution of β decay will be affected.
2 2 −2ρ 3 ρ −2ρ 3(1+x ) ρ(1−y ) Aβ = 1+ρ2 5 − 5 → 1+ρ2 (1−xy) 5(1+y2) − 5(1+y2) q h q i
2 2 −2ρ 3 ρ −2ρ 3(1+x ) ρ(1−y ) Bν = 1+ρ2 5 + 5 → 1+ρ2 (1−xy) 5(1+y2) + 5(1+y2) q h q i 2 and Rslow =0 → y
2 2 where x ≈ (ML/MR) − ζ and y ≈ (ML/MR) + ζ
are RHC parameters that are zero in the SM. ⇒ Precision measurements test the SM
Goal must be . 0.1% (see Profumo, Ramsey-Musolf and Tulin, PRD 75 (2007))
July 25, 2012 Dan Melconian – 13 REU presentation The Gameplan:
Z Z∓1 ± AX −→ AY + e + νe ● perform a β decay experiment pν on short-lived isotopes
θe,ν pβ
pX =0
pY
July 25, 2012 Dan Melconian – 14 REU presentation The Gameplan:
Z Z∓1 ± AX −→ AY + e + νe ● perform a β decay experiment pν on short-lived isotopes
θe,ν pβ ● make a precision measure- ment of the angular correla- tion parameters
pX =0
pY
July 25, 2012 Dan Melconian – 14 REU presentation The Gameplan:
Z Z∓1 ± AX −→ AY + e + νe ● perform a β decay experiment pν on short-lived isotopes
θe,ν pβ ● make a precision measure- ment of the angular correla- tion parameters
● compare the SM predictions p =0 X to observations pY
July 25, 2012 Dan Melconian – 14 REU presentation The Gameplan:
Z Z∓1 ± AX −→ AY + e + νe ● perform a β decay experiment pν on short-lived isotopes
θe,ν pβ ● make a precision measure- ment of the angular correla- tion parameters
● compare the SM predictions p =0 X to observations pY ● look for deviations as an indication of new physics
July 25, 2012 Dan Melconian – 14 REU presentation Wu’s experiment
July 25, 2012 Dan Melconian – 15 REU presentation Wu’s experiment
● so much scattering! ● low polarization ● short relaxation time ● poor sample purity ● pain to flip spin ● need long t1/2
July 25, 2012 Dan Melconian – 15 REU presentation Traps around the world
Many groups around the world realize the potential of using traps for precision weak interaction studies
atom traps ion traps He
Na K Fr planned
Na Rb
July 25, 2012 Dan Melconian – 16 REU presentation Neutral Atom Traps
Any type of trap requires a velocity-dependent force to cool an object
lbs lbs
July 25, 2012 Dan Melconian – 17 REU presentation Neutral Atom Traps
Any type of trap requires a velocity-dependent force to cool an object . . . as well as a position-dependent force that defines x =0
lbs lbs
lbs
July 25, 2012 Dan Melconian – 17 REU presentation Neutral Atom Traps
Any type of trap requires a velocity-dependent force to cool an object . . . as well as a position-dependent force that defines x =0
Laser light −→ velocity-dependent force
lbs Zeeman effect −→ position-dependent force
July 25, 2012 Dan Melconian – 17 REU presentation Neutral Atom Traps
Any type of trap requires a velocity-dependent force to cool an object . . . as well as a position-dependent force that defines x =0
Laser light −→ velocity-dependent force
lbs Zeeman effect −→ position-dependent force
=⇒ atom trap = damped harmonic oscillator ⇐=
July 25, 2012 Dan Melconian – 17 REU presentation Atom-Photon Interactions
How can light seriously affect a thermal atom?
vs.
1 2 2 Mv = kB T 2π 6.28 ~c = (197.3 MeV fm)( ) 6 2 λ 770 nm Mv = 2(40×10 keV/c ) −6 h =1.6 × 10 MeV 1/2 × −8 (8.62 10 keV/K)(295 K)i ⇒ ~k ∼ 1.6 eV/c ⇒ Mv ∼ 45 keV/c
July 25, 2012 Dan Melconian – 18 REU presentation Atom-Photon Interactions
Cycling Transitions!
vs.
~k × 30, 000 ≈ Mv
July 25, 2012 Dan Melconian – 18 REU presentation However. . . . cycling transition ⇒ not everything trappable H He Li Be BOCN F Ne Na Mg AlSiP S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In SnSb Te I Xe Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl PbBi Po At Rn Fr RaLr Rf Db Sg Bh Hs Mt Ds Rg
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Hd No
July 25, 2012 Dan Melconian – 19 REU presentation However. . . . cycling transition ⇒ not everything trappable H He Li Be BOCN F Ne Na Mg AlSiP S Cl Ar K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In SnSb Te I Xe Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Tl PbBi Po At Rn Fr RaLr Rf Db Sg Bh Hs Mt Ds Rg
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Hd No
and still the trap is shallow...
July 25, 2012 Dan Melconian – 19 REU presentation Still, gotta love it!!
σ+ I σ− σ− ● isomerically selective! ion beam neutralizer I
σ+ σ+
σ−
Raab PRL 59 (1987)
July 25, 2012 Dan Melconian – 20 REU presentation Still, gotta love it!!
σ+ I σ− σ− ● isomerically selective! ● ion beam point-like source! neutralizer 3 I (. 1 mm FWHM)
σ+ σ+
σ−
Raab PRL 59 (1987)
July 25, 2012 Dan Melconian – 20 REU presentation Still, gotta love it!!
σ+ I σ− σ− ● isomerically selective! ● ion beam point-like source! neutralizer 3 I (. 1 mm FWHM) ● cold atoms! (. 1 mK)
σ+ σ+
σ−
Raab PRL 59 (1987)
July 25, 2012 Dan Melconian – 20 REU presentation Still, gotta love it!!
σ+ I σ− σ− ● isomerically selective! ● ion beam point-like source! neutralizer 3 I (. 1 mm FWHM) ● cold atoms! (. 1 mK) ● backing-free source! σ+ σ+
σ−
Raab PRL 59 (1987)
July 25, 2012 Dan Melconian – 20 REU presentation Still, gotta love it!!
σ+ I σ− σ− ● isomerically selective! ● ion beam point-like source! neutralizer 3 I (. 1 mm FWHM) ● cold atoms! (. 1 mK) ● backing-free source! σ+ σ+
σ−
Raab PRL 59 (1987) an ideal source of radioactives for β-decay experiments!
July 25, 2012 Dan Melconian – 20 REU presentation Coupling a MOT to ISAC-I
σ+ I σ− σ−
K+ ion beam Zr neutralizer I
+ σ+ σ
σ−
37K yield with 40 µA on TiC #1: 6 × 107/s
July 25, 2012 Dan Melconian – 21 REU presentation Double-MOT system
July 25, 2012 Dan Melconian – 22 REU presentation Double-MOT system
Traps provide a backing-free, cold (. 1 mK), localized (. 1 mm3) source of short-lived radioactive atoms
Detect pβ and precoil ⇒ deduce pν!
July 25, 2012 Dan Melconian – 22 REU presentation The TRINAT lab
July 25, 2012 Dan Melconian – 23 REU presentation The TRINAT lab
July 25, 2012 Dan Melconian – 23 REU presentation The new chamber
BC408 (anti)Helmholtz coils 500µm thick Be foil lcrnMCP electron recoil MCP
● Shake-off e− detection ● Better control of OP beams ● Bquad → BOP quickly: AC-MOT electrostatic hoops (Harvery & Murray, PRL 101 (2008) 100µm thick ● Si-coated BB1 Si-strip Increased β/recoil solid angles mirror detector ● Stronger E-field 40x40mm2x300µm ● . . . July 25, 2012 Dan Melconian – 24 REU presentation The new chamber
BC408 (anti)Helmholtz coils 500µm thick Be foil lcrnMCP electron recoil MCP
● Shake-off e− detection ● Better control of OP beams ● Bquad → BOP quickly: AC-MOT electrostatic hoops (Harvery & Murray, PRL 101 (2008) 100µm thick ● Si-coated BB1 Si-strip Increased β/recoil solid angles mirror detector ● Stronger E-field 40x40mm2x300µm ● . . . July 25, 2012 Dan Melconian – 24 REU presentation Outline of polarized experiment
355 nm
F = I + J ± S1/2 σ 3 I = 2 1 J = 2 mF = −2 −10 1 2
July 25, 2012 Dan Melconian – 25 REU presentation Outline of polarized experiment
355 nm
D trapping 2 light
anti-Helmholtz
F = I + J ± S1/2 σ 3 I = 2 1 J = 2 mF = −2 −10 1 2
July 25, 2012 Dan Melconian – 25 REU presentation Outline of polarized experiment
355 nm D pumping 1 light
P1/2
Helmholtz (2 G)
F = I + J ± S1/2 σ 3 I = 2 1 J = 2 mF = −2 −10 1 2
July 25, 2012 Dan Melconian – 25 REU presentation Outline of polarized experiment
photoionization 355 nm D pumping 1 light
P1/2
Helmholtz (2 G)
E-field ± F = I + J + S1/2 σ K 3 MCP I = 2 1 J = 2 mF = −2 −10 1 2
July 25, 2012 Dan Melconian – 25 REU presentation Atomic measurement of P
P1/2
deduce P based on a model of the excited state populations: ± S1/2 σ mF = −2 −10 1 2
+0.19 ⇒ Pnucl = 96.74 ± 0.53−0.73
July 25, 2012 Dan Melconian – 26 REU presentation Atomic measurement of P
P1/2 week ending PRL 101, 173201 (2008) PHYSICALREVIEWLETTERS 24 OCTOBER 2008
for MOT currents rapidly switched to zero, the induced eddy currents continue to produce B fields until theydeduce too P basedMOT on Current a model of the reduce to zero. In practice the B field due to the MOT takes 10 msexcitedto state populations: <10 À7 T Switch on reduce to , this time depending on the proximity± Electron Spectrometer S1/2 of conductors to the coils, their shape, andσ resistivity. σ + During this time, a large fraction of trapped atoms escape, resulting in a cold atom density that rapidly falls to zero. Laser Polarization mF = −2 −10 1 2 Losses can be reduced by leaving the cooling lasers on to σ - create an optical molasses (if this does not interfere with the experiment); however, the loss problems remain. The 0 2 4 6 8 10 12 14 16 comparatively long time taken for the B field to decay also Time (ms) reduces data accumulation rates, since the repetition rate is FIG. 1 (color online). The switching configuration for the ac then only 50 Hz . MOT. The MOT is driven by an alternating supply, so that the net It is clearly advantageous to eliminate these constraints. induced current in conductors surrounding the MOT coils is Several methods have been attempted, including shaping zero. The polarization of the six trapping laser beams is switched the dc MOT driving current at switchoff to try to cancel at the same rate as the MOT current, so as to maintain trapping. fields due to eddy currents [ 10 ]. This technique is compli- Experiments using charged particles are conducted during the cated and requires different currents when spectrometer time the MOT current is zero.
+0.19 ⇒ Pnucl = 96.74 ± 0.53−0.73
July 25, 2012 Dan Melconian – 26 REU presentation Measuring Aβ — Fall 2012(?)
N(σ+) − N(σ−) Asymmetry = N(σ+) − N(σ−)
BB1 Si-strip pe detector ∼ PAβ Ee lcrnMCP electron e− ±I
β+
BC408
July 25, 2012 Dan Melconian – 27 REU presentation Measuring Bν (and D)
ˆ i (pβ ×pˆν) dW ∼ P Bν pˆν ˆi + P D Eβ MCP
pˆβ ≈ zˆ ⇒ pν ≈−pAr
−zˆ
yˆ E-field Ar+ OP beam ν xˆ
β+
July 25, 2012 Dan Melconian – 28 REU presentation Measuring Bν (and D)
ˆ i (pβ ×pˆν) dW ∼ P Bν pˆν ˆi + P D Eβ MCP
pˆβ ≈ zˆ ⇒ pν ≈−pAr
−zˆ
yˆ E-field Ar+ OP beam ν xˆ
β+
July 25, 2012 Dan Melconian – 28 REU presentation Measuring Bν (and D)
ˆ i (pβ ×pˆν) dW ∼ P Bν pˆν ˆi + P D Eβ MCP
pˆβ ≈ zˆ ⇒ pν ≈−pAr
−zˆ
yˆ E-field Ar+ OP beam xˆ asymmetry ∼ P B ν xˆ ν yˆ asymmetry ∼ P D β+
July 25, 2012 Dan Melconian – 28 REU presentation The neutrino asymmetry measurement Ar A Ar A
st SM 1 : Bν = (0.995 ± 0.040)Bν (stat) nd SM 2 : Bν = (0.975 ± 0.031)Bν (stat) Ar A SM ⇒ Bν = 0.981(26)(17)Bν (Melconian, PLB 649 (2007) 370) July 25, 2012 Dan Melconian – 29 REU presentation Goal, in terms of RHCs
Expected limits if Aβ,Bν and Rslow all measured to 0.1%
see Profumo, Ramsey-Musolf and Tulin, PRD 75 (2007) 075017
July 25, 2012 Dan Melconian – 30 REU presentation Beyond the minimal L-R symmetric model
(adapted from Thomas et al., Nucl Phys A 694; see also Severijns, Beck and Naviliat-Cuncic, Rev Mod Phys 78 (2006)) different experiments are complementary
July 25, 2012 Dan Melconian – 31 REU presentation Summary
● SM is fantastic, but incomplete ● many exciting avenues to find more complete model ● needed: precision measurement of correlation parameters ● (AC-)MOT + opt. pumping = cool physics
July 25, 2012 Dan Melconian – 32 REU presentation Summary
● SM is fantastic, but incomplete ● many exciting avenues to find more complete model ● needed: precision measurement of correlation parameters ● (AC-)MOT + opt. pumping = cool physics
Don’t get married five days before you’re supposed to give a talk! ;-)
July 25, 2012 Dan Melconian – 32 REU presentation Main collaborators/thanks
Cyclotron Institute: P. Shidling, B. Fenker, M. Mehlman, S. Behling, J.C. Hardy, R. Tribble, G. Chubaryan, L. Trache, staff, . . .
TRIUMF: J.A. Behr, A. Gorelov, M. Anholm M.R. Pearson, K.P. Jackson, P. Bricault, M. Dombsky, . . .
Tel Aviv: D. Ashery, I. Cohen Manitoba: G. Gwinner
Funding/Support: DOE DE-FG02-93ER40773, Early Career ER41747 TAMU/Cyclotron Institute
July 25, 2012 Dan Melconian – 33 REU presentation