Neutrons, Mirror Symmetry and New Interactions Stefan Baessler 1. - - PowerPoint PPT Presentation

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Neutrons, Mirror Symmetry and New Interactions Stefan Baessler 1. - - PowerPoint PPT Presentation

Jul 14, 2023 162 likes •461 views

Neutrons, Mirror Symmetry and New Interactions Stefan Baessler 1. Production of Low Energy Neutrons 2. Experiments with Low Energy Neutrons: The search for the origin of Parity Violation Spectroscopy of gravitationally bound quantum

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SLIDE 1

Stefan Baessler Neutrons, Mirror Symmetry and New Interactions

  • 1. Production of Low Energy Neutrons
  • 2. Experiments with Low Energy Neutrons:
  • The search for the origin of Parity Violation
  • Spectroscopy of gravitationally bound quantum states
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SLIDE 2

The Spallation Neutron Source SNS in Oak Ridge, TN

Linear H- accelerator Accumulator ring (buncher) Target Target Guide Hall

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SLIDE 3

5 - Cold Neutron Chopper Spectrometer 13 - Fundamental Physics Beamline 11A - Powder Diffractometer Commission 2007 12 - Single Crystal Diffractometer Commission 2009 7 - Engineering Diffractometer IDT CFI Funded Commission 2008 6 - SANS Commission 2007 9 – VISION

Usage of neutrons @ SNS

1B - Disordered Mat’ls Commission 2010 2 - Backscattering Spectrometer Commission 2006 3 - High Pressure Diffractometer Commission 2008 4A - Magnetism Reflectometer Commission 2006 4B - Liquids Reflectometer Commission 2006 Commission 2007 18 - Wide Angle Chopper Spectrometer Commission 2007 17 - High Resolution Chopper Spectrometer Commission 2008 Commission 2008 14B - Hybrid Spectrometer Commission 2011 15 – Spin Echo

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SLIDE 4

Table of Contents

  • 1. Production of Low Energy Neutrons
  • 2. Experiments with Low Energy Neutrons:
  • The search for the origin of Parity Violation
  • Spectroscopy of gravitationally bound quantum states

p+ n e-

e

ν

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SLIDE 5

Parity Violation in Nature

Mechanics: Parity violation by convention Pedals of a bicycle: Parity is conserved

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SLIDE 6

Parity Violation in (Bio)chemistry

Chemistry / biology: Parity of in amino acids Problem: chemical properties of enantiomeres mostly identical, still we have preferred chirality for sugars and amino acids in biological systems. Why? Measurement of optical activity

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SLIDE 7

The Beta Decay Hamiltonian

Parity Violation found by Wu et al, 1956

ud 5 F weak 5

h.c. 2 1

  • e

G H p γ γ γ n e γ γ γ ν V

µ µ

λ

−

= ⋅ + − +

60Co

I

  • e-

60Co

I

  • e-

≠

Fermi’s golden rule:

2 weak

2 Decay probability

i f

w f H i π ρ

→ =

2

d n = (ddu) p = (udu) u WL

±

e- νe gV , gA

forbidden at low energy, due to high m(WR)

d n = (ddu) p = (udu) u WR

±

e- νe gV , gA

Left –Right-Symmetric model:

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SLIDE 8

1 cos

e e e

p dw a E

ν

θ   ∝ +    

n e-

e

ν

eν

θ p

Idea of the cos θeν spectrometer Nab @ SNS

Kinematics:

  • Energy Conservation:
  • Momentum Conservation

2 2 2 e e p

2 cos

e

p p p p p

ν ν ν

θ = + +

e,max e

E E E

ν =

−

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SLIDE 9

The cosθeν spectrometer Nab @ SNS

Segmented Si detector Neutron beam decay volume TOF region transition region acceleration region

30 kV

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SLIDE 10

Possible future setup of Nab

Detector Beam Line Neutrons Beam Stop Electrons +Protons Decay volume

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SLIDE 11

The Nab collaboration

  • R. Alarcona, L.P. Alonzib , S.B.b (Experiment Manager), S. Balascutaa, J.D. Bowmanc (Co-

Spokesmen), M.A. Bychkovb, J. Byrned, J.R. Calarcoe, T.V. Ciancioloc,

  • C. Crawfordf, E. Frležb, M.T. Gerickeg, F. Glückh, G.L. Greenei, R.K. Grzywaczi, V. Gudkovj,

F.W. Hersmane, A. Kleink, J. Martinl, S. Pageg, A. Palladinob, S.I. Penttiläc (On-site Manager),

  • D. Počanićc (Co-Spokesmen), K.P. Rykaczewskic, W.S. Wilburnk, A.Youngm

a Department of Physics, Arizona State University, Tempe, AZ 85287-1504 b Department of Physics, University of Virginia, Charlottesville, VA 22904-4714 c Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 d Department of Physics and Astronomy, University of Sussex, Brighton BN19RH, UK d Department of Physics and Astronomy, University of Sussex, Brighton BN19RH, UK e Department of Physics, University of New Hampshire, Durham, NH 03824 f Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 g Department of Physics, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada h IEKP, Universität Karlsruhe (TH), Kaiserstraße 12, 76131 Karlsruhe, Germany i Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996 j Department of Physics and Astronomy, University of South Carolina, Columbia, SC 29208 k Los Alamos National Laboratory, Los Alamos, NM 87545 l Department of Physics, University of Winnipeg, Winnipeg, Manitoba R3B2E9, Canada m Department of Physics, North Carolina State University, Raleigh, NC 27695-8202

Tasks of UVa group: Spectrometer design, Superconducting magnet, Proton source

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SLIDE 12

Table of Contents

  • 1. Production of Low Energy Neutrons
  • 2. Experiments with Low Energy Neutrons:
  • The search for the origin of Parity Violation
  • Spectroscopy of gravitationally bound quantum states
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SLIDE 13

The neutron source of the ILL / Grenoble

The neutron source of the ILL Grenoble/France

Institut Laue-Langevin (neutrons) European Synchrotron Radiation Facility

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SLIDE 14

Examples: Bound States

electron

Electromagnetic Bound State Gravitational Bound State

neutron proton Nucleus (12C)

Strong Interaction Bound States u d d

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SLIDE 15

Gravitational Bound states – The idea

neutron

neutron

Absorber/Scatterer

; mgz z >  =

g

E1 = 1.41 peV E2 = 2.46 peV E3 = 3.32 peV

Energy [peV] 1 2 3 4

Ψ1 Ψ2 Ψ3 Ψ4 E4 = 4.08 peV

Early proposals:

  • Neutrons: V.I. Lushikov (1977/78),

A.I. Frank (1978)

  • Atoms: H. Wallis et al. (1992)

; ; otherwise mgz z V >  =  ∞ 

Height [µm]

10 20 30 40 1

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SLIDE 16

2002 2002 2002 2002年世界十大科技进展新闻揭晓 年世界十大科技进展新闻揭晓 年世界十大科技进展新闻揭晓 年世界十大科技进展新闻揭晓（ （ （ （图 图 图 图） ） ） ） CCTV.com消息（晚间新闻）: 两院院士今天还评出了2002年世界十大科技进展新闻。2002年世界十大科技进 展新闻分别是：

1 科学家首次大批量制造反物质并首次观察到反物质原子内

部结构：世界各地9个研究所、39名科学家的通力合作下，欧洲核 子研究中心已成功制造出约5万个低能量状态的反氢原子，这是人 类首次在受控条件下大批量制造反物质，这对准确比较物质与反物 质的差别、解答宇宙构成等问题有重要意义。欧洲核子研究中心的 一个国际科学家小组首次成功地对反物质原子的内部结构和物理特

  • 3 科学家观测到引力场中的量子效应：一个国际合作的研究小组在1月17日

出版的英国《自然》杂志上，报告了他们对于地球重力场量子化的观测结果。 他们让冷却到非常接近绝对零度的中子在重力场中运动，同时用一个探测器观 测中子的下落。结果他们发现，中子的下落过程不是连续的，而是从一个位置“ 跳”到了另外一个位置，这一过程与理论的预测相符合，从而实际观测到了引力 场的量子效应。 性进行了研究，朝弄清物质与反物质的差别、进而验证物理学基本 理论迈出关键一步。

  • 2 英、美、德等国科学家破译老鼠基因组：来自英、美、德等国的

上百位科学家12月5日在英国《自然》杂志上联合宣布他们成功破译了 老鼠的基因组。人类与老鼠共享着80％的遗传物质和99％的基因，因 此了解老鼠非常有助于了解人类自身。新的基因组草图显示，老鼠的 20对染色体上共有约25亿个碱基对，与人类23对染色体上的29亿个碱 基对相当接近。DNA链上基因与基因之间的“空白”片断也非常相似。 两个物种的基因数目大约都是3万个，其中绝大部分相同，只有几百个 基因是某一物种独有的。 场的量子效应。

  • 4 中、美、日科学家发现核反应堆中微子消失现象：12月6日，日、美、中

三国的科学家同时宣布他们发现了核反应堆中微子消失的现象，这意味着反应 堆产生的中微子发生了振荡，变成了另外一种没有被探测到的中微子，从而确 认了太阳中微子发生了振荡，并确定中微子振荡的关键参数。这是首次在人工 中微子源中发现中微子消失。

[… and 6 other discoveries]

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SLIDE 17

e [Hz]

0.04 0.05

Ultra-cold neutron transmission through slit

Absorber Height h [m]

10 20 15 25 5

count rate [

0.01 0.02 0.03

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SLIDE 18

Incomplete List:

  • Astronomy and Cosmology
  • Particle accelerators (additional decay modes)
  • Conversion of Galactic Axions in a magnet field into microwave photons:

α γ f

Possible experimental signatures of Axions

  • Light shining through walls:
  • Short-range spin-dependent forces between Fermions

γ (external magnetic field)

LASER

wall

PM

  • magn. field
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SLIDE 19

e [Hz]

0.04 0.05

Spin up + Spin down

( )

1 2 2 2 2

ˆ 1 1 ( ) exp 8

S P

r V r g g r m c r r σ ⋅   = − + − λ   π λ  

Ultra-cold neutron transmission through slit

tential V Absorber

Absorber Height h [m]

10 20 15 25 5

count rate [

0.01 0.02 0.03

Spin down Spin up

Poten Height z Mirror Ab

; ; otherwise z z V V mg ∆ + >  =  ∞ 

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SLIDE 20

Projected improvement: Polarized experiment

25 mm

Position-sensitive neutron detector B0 up

  • r

B0 down Bottom mirrors Absorber/Scatterer Magnetization UCN Spin transport zone Polarizing foil with guide field wires

Absorber Height h[m] Count rate [s-1]

10 20 30 0.02 0.04 0.06

Sensitivity gain due to relative measurement, stronger UCN source, wider mirror, longer run time. False effect: Transverse Stern-Gerlach (Cross-check: velocity-dependence, dependence on size of holding field) False effect due to magnetic field gradient > 1 T/cm from ferromagnetic particles in mirror (Cross-check: demagnetization) Experiment to be performed in 2010-11

  • S. Baeβler et al., NIM, 2009
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SLIDE 21

Spectroscopy on gravitationally bound states

V E1 E2 E3

Transition 2 ↔ 3 Idea: Induce state transitions through:

  • Oscillating magnetic field gradients
  • Oscillating Masses

Accuracy of position-type observables: ~ 10% Improvement: do spectroscopy

z

  • Vibrations

Typical energy differences: E ~ h·260 Hz

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SLIDE 22

Theory of resonance transitions

“Rabi oscillations” Resonance behavior

0.2 0.4 0.6 0.8 1.0

  • ax. transition probability

τpassage = 0.5 s

τpassage = 0.05 s

3 → 1 4 → 1 2 → 1

0.2 0.4 0.6 0.8 1.0

Transition probability 3→1 ω = 0.95ω13 ω = ω13

( )

13 3 1

1 E E ω = −

  • ( )

13

1 3 1 + small terms V z Ω =

0.2

max

200 400 600

ω/2π [Hz]

2 2 2 n

( ) cos 2 , defines H mgz V z t m z H N ω ∂ = + + ⋅ ∂

  • Schrödinger

equation:

( )

( ) ( )

2 passage 2 2 13 13 2 3 1 passage 13 2 2 13 13

sin 2 P τ ω ω τ ω ω

→

  − + Ω     = Ω − + Ω

Rabi formula:

0.05 0.10 0.20 0.15

τpassage [s]

0.0

Tra

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SLIDE 23

Projected first measurement of resonance transitions

New UCN Source

  • 1. Prepare initial state,

ground state suppressed

  • 3. Filter ground state
  • 2. Induce transitions in periodic

magnetic field gradient

Position De

  • 4. Measure horizontal

velocity in position- sensitive detector Bottom mirror

1 mm 1 cm

Magnetic holding field B0 velocity vhor ation freq. ω

ion-sensitive Detector

Bottom mirror

1. Prepare initial state (mostly the 3rd), ground state suppressed 2. Induce Transitions 3→1 in time-dependent magnetic field gradient 3. Filter ground state 4. Detect neutrons in dependence of free fall height (corresponding to horizontal velocity, corresponding to oscillation frequency)

  • G. Pignol et al., Thesis UJF Grenoble, 2009

Horizontal UCN ve

  • Mag. Field oscillati
slide-24
SLIDE 24

GRANIT setup

probably dual use, interest for a UCN reflectometer

  • M. Kreuz et al., NIM, 2009
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SLIDE 25

Projected first measurement of resonance transitions

New UCN Source

  • 1. Prepare initial state,

ground state suppressed

  • 3. Filter ground state
  • 2. Induce transitions in periodic

magnetic field gradient

Position De

  • 4. Measure horizontal

velocity in position- sensitive detector Bottom mirror

1 mm 1 cm

Magnetic holding field B0

ion-sensitive Detector

Bottom mirror

  • G. Pignol et al., Thesis UJF Grenoble, 2009

3 → 1 4 → 1

  • Mag. Field oscillation freq. ω
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SLIDE 26

The GRANIT spectrometer in storage mode

  • 1. Population of

ground state

  • 2. Populate the initial state
  • 3. Study transition to “final state”
  • 4. Neutron Detection

30-50 cm

  • 4. Neutron Detection

Challenge: Tolerances to get a high neutron lifetime in a given state:

Flatness of bottom mirror: < 100 nm Accuracy of setting the side walls perpendicular: ~ 10-5 Vibrations, Count rate, Holes, Vacuum, Dust, … RESULTS IN STORAGE MODE: 2012 ???

  • G. Pignol, Thesis UJF Grenoble, 2009
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SLIDE 27

Institut Laue-Langevin: H.G. Börner

  • M. Kreuz

V.V. Nesvizhevsky LPSC Grenoble:

  • F. Naraghi

K.V. Protasov

  • F. Vezzu

U Heidelberg (former member):

  • H. Abele
  • A. Westphal
  • F. Ruess

The GRANIT collaboration

V.V. Nesvizhevsky

  • T. Soldner (also: TUM)
  • M. Thomas

PNPI Gatchina: A.M. Gagarski L.A. Grigorieva T.K. Kuzmina

  • G. Petrov

Lebedev Institute Moscow: A.Y. Voronin JINR Dubna: A.V. Strelkov University of Virginia:

  • J. Prince

S.B.

  • F. Vezzu
  • D. Rebreyend
  • G. Pignol

LMA Villeurbanne:

  • R. Flaminio
  • C. Michel
  • N. Morgado
  • L. Pinard

University of Rhodes Island: A.E. Meyerovitch ISSP Moscow: L.P. Mezhov-Deglin PSI Villigen:

  • P. Schmidt-Wellenburg
  • F. Ruess
  • S. Nahrwold
  • C. Krantz
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SLIDE 28

The final slide

Thank you for your attention!