Schleching 2/2008 3.1 Präzisionsphysik mit Neutronen/3. n- Experimente jenseits des SM...

Schleching 2/2008 3.1Präzisionsphysik mit Neutronen/3. n- Experimente jenseits des SM

Präzisions-Physik mit Neutronen1.Neutronenquellen2.Physik mit Neutronen, allgemein3.Neutronen-Experimente: jenseits SM4.Theorie Standard Modell5.Neutronen-Experimente: diesseits SM6.Theorie n-Zerfall

D. DubbersU. Heidelberg


1. Neutronenquellen1.1 Reaktor Neutronenquellen1.2 Spallations-Neutronenquellen1.3 Ultrakalte Neutronen


2. Physik mit Neutronen allgemein 2.1 Neutronen-Streuung2.3 Angewandte Neutronenphysik


Besonderheiten des Neutrons

Neutronen:• sehen besonders gut die leichten Atome (z.B. Wasserstoff-Brücken)• sehen einzelne Isotope (Kontrastvariation)• sehen Magnetismus (Spintronik)• sehen Bewegungen der Moleküle, Spins, (auch sehr langsame)

separat für alle Längenskalen (En ~ Anregungsenergien des Festkörpers, λn ~ Gitterkonstante des Festkörpers)

• sehen getrennt kohärente und inkohärente Prozesse • (Paar- und Autokorrelations-Funktionen)• machen wenig Vielfachstreuung• sind meist sehr durchdringend


3.Neutronen-Experimente jenseits des SM3.1 Einführung3.2 Einige Experimente


3.1 Einführung Temperature kT = 10+19 GeV Planck scale

10+16 GeV Grand Unification Inflation ... ... wenn H = å/a ≈ const. Chiral phase transition Nucleon freeze out Electroweak transition Nuclear freeze out Atomic freeze out

Galactic freeze out 10-11 GeV (T = 2.726 K) Big Bang 10-43 s 10-35 s 10-12 s 1 s 105 y 109 y today Time

…

t

History of the universe: a succession of phase transitions


The Standard Model of particle physics …small input: SYMMETRIES Gauge principle: ψ'(x) = eiθ(x) ψ(x)

('principia') applied to U(1)×SU(2)×SU(3),(+ Lorentz x' = L·x, + CPT etc. invariances, …)

rich output: INTERACTIONS basis for:

→ equations of motion Maxwell, technology,Schrödinger, chemistry,Dirac, molec. biology, … solar/nuclear power,

→ existence of photons, gluons, W±, Z0 (= carriers of interaction)

→ conservation of charges (= sources of interaction)

→ generation of masses

…is very successful ...

ψ:

ψ':


… but is only part of the picture:Unsolved problems:

3 particle families 12 masses →4 quark-phases + 4 lepton-phases

gravitation and quantum mechanicsbaryon-asymmetry of universe →

mass-energy content of universe …

Test all laws of physics with the highest possible precision(including energy conservation, Lorentz-, CPT-invariance, …).

To be tested, laws must be well known: this is the case mostly in the electroweak and the gravitational sector.


Particle physics at the lowest energies

0.1 0.5 1 5 10 50 100EnergyTeV

0.2

0.512

510

langiSa.u

.

ENERGY DEPENCE OF PROPATATOR

0.1 0.150.2 0.3 0.5 0.7 1EnergyTeV

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ENERGY DEPENCE OF PROPATATOR

.at very highest isPrecision precision.high is countsWhat then

TeV. 10neV 1at or TeV 0.5or 10at worksonewhether small, very i.e. ,1/ :same thebe willpropagator then the

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MM

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Precision reached in low-energy work- in energy: δE < 10─23 eV = ± 0.000 000 000 000 000 000 000 01 eV

reached in high-precision ultracold neutron and atom work

- in momentum: δp/p < 10─11: 1Å/10m preached in state-of-the-art neutron optics δp

- in mass: δm/m = ±10─11

reached in atomic mass spectrometry

- in time: δt/t = ±10─16

reached with atomic clocks

- in spin-polariz.: δP < 10─7

reached in polarized neutron work


Low energy: mostly 1st family

quarks leptons3rd: b t τ ντ

2nd: s c μ νμ

1st : d u e νe

first family is:- abundant, - long-lived, - useful.


↕ y← L →E=60 kV/cm

υ

earth.) of charge from derived bemay bounds rigorous, lessbut stringent, (More

1.0·10

C 10 ~ 0004(11) 000 000 000 000 000 0.000 1988) Gähler, (R. 10)1.14.0( Charge

N 10 Force

m/s 200 m, 10over Å 82

field electricin beam-n of deflection From

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3.2 Einige Experimente: 1. Why is charge quantized?


Theory of charge quantization

1940 1960 1980 200010-30

10-20

10-10

100

q n/e

year

upper limit on neutron charge

εqLBqLB

LBLBεq

q

q

qqq

:1) ( neutron 0 :)0( atom-H

:number lepton ,number baryon with )(

permits :example possible, extensionsMany

0

anything :family -3

:, for sPredictionquantized. is charge electricy certain whfor known not isIt

n

H

Hn

neutrino Dirac massive

:Theories Unified Grand

Model Standard


Big Bang theory: baryon density ~ 10−18 photon densitybaryon density = antibaryon density

Observation: baryon density ~ 10−9 photon densitybaryon density >> antibaryon density

possible explanation: Violation of 'CP-symmetry'

Experimentum crucis:Electric Dipole Moment dn of the neutron:

if 'CP' explanation is right: dn = 10−27 1 e cm= value required to explain our existence

if 'CP' explanation is wrong: dn = 10−32 1 e cm= value predicted by the Standard Model

Meas.time t from uncertainty rel. N Δφ ~ 1 with Δφ = ωBohr t = dn·E/ħ t,

i.e. error ΔN Δφ = N ½ ΔωBohr t = (ρUCNV)½ ΔdnE t ~ 1

~ 1 Bohr-period/year ~ 10−23 eV

2. Why has so much matter survived the Big Bang?

60 years of instrument

development

M.v.d. Grinten, K. Jungmann, Sa vorm., S. Paul, Di abend


3. Are there extra spatial dimensions?

al.)et DeKieviet (M. echo-spin beam atomic reflection quantum •al.)et sky Neszvishev V. Abele, (H. field nalgravitatio searth' in theon quantizati (UCN) •

:probes with sExperiment

bodies. with progress Large

scale.length dependent -model aon , a tolead wouldThis

. i.e. ed,compactifi 7 dimensions time-space alconvention 4

:e.g. ,dimensions extra requiren gravitatio quantum of theoriesViable

atom Coldneutron Ultracold

cmicroscopi

cmacroscopi

law sNewton' of onmodificati

dimensions up curled


Neutron quantization in the earth's gravitational fieldUltracold neutrons (UCNs) probe Newton's law in the μ-meter and the pico-eV range, set limits on such extra forces.

0 1.4 2.5 3.3 4.1 peV

40 μm30 μm20 μm10 μm 0


UCN gravitational levels

Neutron density above the mirror measured with a position-sensitive detector with spatial resolution of 1.5 μm

Measurement of neutron transmission as a function of the height of the absorber above the neutron mirror.


Experimental limits on non-Newtonian gravity

Yukawa Newton

e 1)( /

λrαr

mMGrV

10 10 10 10 10 -9 -8 -7 -6 -5 4

8

12

16

20

24

28

32 10 10 10 10 10 -9 -8 -7 -6 -5

4

8

12

16

20

24

28

32

[m]

7 8

4

6

5

3 2

1

log 1

0 |

|

current experimental limits:

neutronAFM Casimir

atomic Casimir

Difficulties of AFM:Electrostatics, geometry, roughness, lateral Casimir force, theory

Ph. Schmidt-Wellenburg, Sa Vorm.; Schleching 2006


Neutrinos oscillate: νe↔ νμ , etc. Δm:

Lepton number oscillations Le ↔ Lμ, etc. 0.05 eV

Kaons oscillate: K ↔ K'Strangeness oscillations S ↔ S 10−18 eV

Do neutrons oscillate? n ↔ nbarBaryon-number oscillations B ↔ B ?

Neutron oscillations allowed in various Grand-Unified Theories

4. Neutron oscillations

a) Is baryon number conserved?


The antineutron

detector

'Appearence experiment':Experimental limit τn nbar > 0.86·108 s (90% c.l.)

m·c2 = <n|H|nbar> < 10−23 eVprobes 105 GeV range (model dependent)Heidelberg-ILL-Padova-Pavia collaboration (M. Baldo-Ceolin et al., 1994)

The magnetically shielded beam < 5 nT

The ILL neutron oscillation experiment


b) Is Dark Matter from a mirror world?Is there a sterile mirror world?

Mohapatra, 2005: n ↔ nmirror

can neutrons spontaneously disappear into sterile,

i.e. unobservable mirror neutrons?

Search for neutron − mirror-neutron oscillations

Experiment: U. Schmidt, spring 2007:

using zero-field spin-echo apparatus at FRM2, and ultrafast 'CASCADE' n-detector

'disappearence experiment' - experimental limit:

NB>0/NB=0 = 1.00002(3) → τn-nmirror > 2.7 s (90% c.l.)

September 2007: New limit from ILL, Serebrov et al.: τn-nmirror > 400 s (90% c.l.)

K. Kirch, Mo Abend?


Summary: low-energy neutron physics beyond S.M.

• Why is charge quantized? (qn)

• Why is so much matter and so little antimatter in the universe? (EDM)• Are there hidden dimensions of space-time? (n-free fall)• Can matter oscillate into antimatter? (n-nbar)• Is there a sterile mirror world? (n-nmirror)… (Paul Di Abend)

Schleching 2/2008 3.1 Präzisionsphysik mit Neutronen/3. n- Experimente jenseits des SM...

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