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  • Mass measurements for fundamental subatomic physics

    Tommi Eronen

    University of Jyväskylä, Department of Physics

    April 12, 2010

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Outline

    • Method, JYFLTRAP • Decay energies from atomic masses for. . .

    • superallowed β emitters (+ mirror decays for SM testing) • neutrino physics • 115In — ultralow β decay Q value

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • JYFLTRAP at IGISOL

    IGISOL

    • Served by JYFL K130 cyclotron; variety of beams available • Stopping reaction products in gas • Fast (≈ ms) and universal — all elements available

    Production of ions

    • Fusion • light-ion induced, 26Mg(p,n)26Al,26Alm • fusion evaporation, 54Fe(32S,3p1n)80Y

    • Fission — light-ion induced (140Te, 135Sn, 131In, 122Pd) • Offline — Electric discharge source ( ie. 76Ge, 76Se)

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Schematic view

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Measurement principle

    In these studies we measure cyclotron sideband frequency

    ν+′ + ν−′ = νc ′ ∼= 1

    q

    m B (1)

    Decay energy Q from masses

    Q = Mparent −Mdaughter = ( νc,daughter νc,parent

    − 1 )

    mdaughter (2)

    Q Precision on the order few ×10−9

    • mass doublets • invariance theorem [G. Gabrielse, Phys. Rev. Lett. 102, 172501 (2009)]

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Prepare a clean sample – purification trap [G. Savard et al., Phys. Lett. A 158, 247 (1991)]

    • Mass resolving power R = M/∆M ≈ 105 Co

    un ts

    / a.

    u. 26Alm 26Al(gs)

    (Purification trap frequency - 4,135,000) / Hz

    100

    101

    102

    0 50 100 150

    ≈ 40 Hz

    26Mg

    750 800 850

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Prepare a clean sample – purification trap?? C

    ou nt

    s / a

    .u .

    54Com + 54Co(gs)

    (Purification trap frequency - 1,992,000) / Hz

    100

    101

    102

    103

    -200 -150 -100 150 200 250

    54Fe

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • High-resolution cleaning

    Reaching R = 106 or more

    0

    100

    200

    -15 -10 -5 0 5 10 15 20 25

    # / A

    rb . u

    ni ts

    Dipole frequency - 1991810 / Hz 54Fe

    0

    10

    20

    30

    -15 -10 -5 0 5 10 15 20 25

    # / A

    rb . u

    ni ts

    Dipole frequency - 1991480 / Hz 54Co, 54Com

    • Time needed: ≈ 200 ms • Here 7 Hz separation

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Frequency determination

    • TOF-ICR • [G. Gräff et al., Z. Phys. A 297, 35 (1980)] • [M. König et al., IJMS 95, 142 (1996)]

    • Ramsey method [N.F. Ramsey, RMP 62, 541 (1990)] [S. George et al., PRL 98, 162501 (2007)]

    M ea

    n tim

    e of

    fl ig

    ht /

    µs

    νRF - 1,991,680.6 (Hz)

    ’co54_4_0_2d.dat’ u ($1-reso):2:3

    150

    180

    210

    240

    -15 -10 -5 0 5 10 15

    54Co+ T1/2 = 193.27 ms

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Superallowed β decays

    • nuclear 0+ β +

    −−→ 0+ decays • isospin T = 1 • pure Fermi transitions • characterized with an ft value

    • f statistical rate function, ∝ Q5EC • t partial half-life t1/2b

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • QEC values of superallowed β emitters

    0

    5

    10

    15

    20

    25

    30

    35

    0 5 10 15 20 25 30 35

    Z

    N

    ISOLTRAP (CERN): 22Mg, 34Ar, 38Ca, 74Rb LEBIT (MSU): 38Ca, 66As Canadian PT (Argonne): 22Mg, 46V

    JYFLTRAP to be published proposed

    10C

    14O

    34Cl

    38Km

    22Mg

    34Ar

    38Ca

    66As

    70Br

    74Rb

    other trap measurements

    26Si

    30S

    42Ti 46V

    50Mn

    54Co

    62Ga

    26Alm

    42Sc

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • QEC values of superallowed β emitters Before Penning traps measurements with reactions • (p,n) threshold • (3He,t) • (p, γ) + (n, γ) • Best results ≈ 100 eV

    Penning trap measurements • Still to do: 10C, 14O, 70Br • To verify old, still quite precise measurements

    QEC (keV)

    34Cl a b c d e

    5489 5490 5491 5492 5493 5494

    QEC (keV)

    38mK a

    b

    c

    d

    6043 6044 6045 6046

    JYFLTRAP

    JYFLTRAP

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Comparison to old

    -3.00

    -2.00

    -1.00

    0.00

    1.00

    14O 54Co50Mn46V42Sc34Cl26 mAl ISOLTRAP

    Canadian PT

    Münich3He,t

    RED: JYFLTRAP D

    if fe

    re nc

    e fr

    om a

    ve ra

    ge (

    ke V

    )

    Parent nucleus

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • corrected ft → Ft

    Conserved vector current (CVC) hypothesis:

    Ft = ft ( 1 + δ′R

    ) (1 + δNS − δC ) =

    K

    2G 2V ( 1 + ∆RV

    ) • ft — experimental, precision 0.1%

    Corrections — 1%: (10% precision needed)

    • δC — isospin-symmetry-breaking • δ′R — NS independent radiative • δNS — NS dependent radiative • ∆RV — transition-independent radiative

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Ft values [J.C. Hardy and I.S. Towner, Phys. Rev. C 79, 055502 (2009)]

    Blue: QEC from JYFLTRAP + 26Al ISOLTRAP, 46V Canadian PT

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Vud of the CKM matrix

     Vud Vus VubVcd Vcs Vcb Vtd Vts Vtb

     |d〉|s〉 |b〉

     =  |d ′〉|s ′〉 |b′〉

     • quark-mass eigenstates |x〉 to weak eigenstates |x ′〉

    Vector coupling constant GV

    GV = GFVud,

    where GF = 1.16637(1)× 10−5 GeV−2.

    Vud = K

    2G 2F ( 1 + ∆VR

    ) Ft

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Vud from different sources

    Vud (0.97xx)

    superallowed 2005 superallowed 2008

    neutron pion

    mirror

    0 10 20 30 40 50 60

    • from superallowed — most precise • newcomer: mirror decays [Naviliat-Cuncic and Severijns, PRL 102, 142302 (2009)]

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • CKM matrix unitarity

    • top-row unitarity requirement: |Vud|2 + |Vus|2 + |Vub|2 = 1 • |Vud|2 from superallowed β decays • |Vus|2 from Kaon decay • |Vub|2 negligible

    Vud 2 ( 0.9XX )

    Hardy1990

    Hardy2005

    Hardy2008

    47 48 49 50 51

    Vus 2 ( 0.0XX )

    48 49 50 51 52

    SUM - 1 ( 10-3 )

    -5 -4 -3 -2 -1 0 1

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Superallowed β decay summary

    • Penning trap QEC value measurements cover all but 10C, 14O • ft precision limited in most cases by branching ratio • Curiosity: in 62Ga ft limited by Q value

    Deviation from Hardy2005 (keV)

    14O Butler (1961)

    Barden (1962) Roush (1970)

    Vonach (1977) White (1977) Tolich (2003)

    -3.0 -2.0 -1.0 0.0 1.0 2.0

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Q value measurements for neutrino studies

    Neutrinos usually associated with normal β decay:

    (A,Z )→ (A,Z + 1) + e− + ν̄e (3) (A,Z )→ (A,Z − 1) + e+ + νe (4)

    But also from double beta decay:

    • 2νββ • extremely weak process, T1/2 > 1020 y

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Q value measurements for neutrino studies

    Double β decay is a 2nd order process

    Some cases (β−β−):

    • 48Ca → 48Ti • 76Ge → 76Se • 100Mo → 100Ru • 124Sn → 124Te • 136Xe → 136Ba • 150Nd → 150Sm

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Two varieties of double β decay

    • Two-neutrino mode (2νββ) • Zero-neutrino mode (0νββ)

    • Only if mν 6= 0 • and ν = ν̄ → neutrino is a Majorana particle → conservation of lepton number breaks

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Two varieties of double β decay

    Detection of 0νββ

    • 2νββ makes huge background • decay branch to 0νββ is very small • One claim: Heidelberg-Moscow 76Ge →76Se

    Mass measurements for fundamental subatomic physics Tommi Eronen

  • Motivation for accurate Q value

    • Need the Q value to be well below detector resolution

    • For phase space calcu