Yuri Kamyshkov/ University of Tennessee

email: kamyshkov@utk.edu

February 25, 2016 Lecture 3 of 3 @ ORICL Philosophical Society

http://web.utk.edu/~kamyshko/ORICL/

All lectures will be posted at

Part 3. What DM can do to neutrons? What is next?

• Dark Matter definitely exists, but the nature of DM is unknown;

• Dark Matter (or part of it) can be in the form of particles coming to Earth;

• DM interaction with OM is very weak (like ~ neutrino interactions)

and are mediated by a new unknown force of nature;

• Existing experimental observations indicate that masses of DM particles

are rather light (few amu) than heavy (thousands of amu);

• Hypothesis of Mirror Matter provides new viable paradigm of DM with DM

consisting of mirror H and He, mirror nuclei and atoms, stars, etc.

• Interaction between two worlds OM and MM (besides gravity) can be due to

exchange (mixing) of neutral particles: photons, neutrinos, neutrons,…

• Mirror H and He (from mirror galactic clouds) can be accumulated at Earth in

the form of unobservable for us mirror atmosphere of H and He and can create

undetectable for us mirror magnetic field inside the Earth.

• Today we’ll discuss how this picture of MM can be detectable with neutrons.

Mass

Spin

Magnetic moment

Magnetic field

Earth gravity

Gas pressure

Neutron total energy

Neutron total energy

1 n nm m amu

12n n

s s

n n

(0 ) ; (?)Earth

B B B

g g

(1 atm vacuum); (?)p p

2 0mc KE B; B

2 0mc KE B ; B

Spin of the neutron

and magnetic moment

Quark structure

of neutron

Magnetic needle aka

magnetic momentMagnetic needle

in Earth mag. fieldHigh and Low potential

energy of magnetic needle

Magnetic field of

magnetic moment

http://www.youtube.com/watch?v=RoSYKPTdlxs

Two pendulums with close eigenfrequencies + small coupling

http://www.youtube.com/watch?v=Z5rKTagEsro&feature=related

Pendulums with different eigenfrequencies and small coupling

n

nPeriod of free oscillations is determined by value of 𝜀

time

Complementarity

of Yin and Yang

means in vacuum

is mixed with

n n

n n

+ n n

“Two-level system in Quantum Mechanics”

Neutron – mirror neutron oscillation in magnetic field

Energy

mixed with n n

+ n n

in vacuum

no no B, B 0B 0B

0B

E B

E BTime

E B

Uncertainty principle: E t

8

To be consistent with Mirror Matter concepts the

presence of mirror magnetic field 𝑩 should be considered

http://pdg.lbl.gov

(Z. Berezhiani, 2009)

2 2

2 2 2 2

2 2

2 2 2

( ) ( ) ( ) cos

sin ( ) sin ( )( )

2 ( ) 2 ( )

sin ( ) sin ( )( )

2 ( ) 2 (

B B B

B

P t p t d t

t tp t

t td t

Neutron disappearance in the presence of

where = and - oscillation time

assymetry

2

1 12 2

det

)

( ) ( )( ) ( ) cos

( ) ( )B B

B collis BB B

B B

N t N tA t N d t

N t N t

;

=

9

B

B

B

oscillations in the presence of n n B

10

n'

Neutron reflected off the wall

Mirror neutron exiting trap

at typical B B

in case of successful guessing for the resonance enhancement is expected: theoscillation frequency will be reduced to (1/few s)and oscillation amplitude increased by few orders of magnitude, ul

B B

timately to

2

Pnn

nn

t

non-resonant magnetic field B B

observation timet

oscillation time > 1 secnn

n n search at ILL / Grenoble (2007)/ A. Serebrov et al.

11

PNPI Experiment to search for nn disappearance

at ILL/Grenoble reactor, A. Serebrov et al (2009)

12

190 L volumestores ~ 500,000 ucn;with wall collision rate

~ 10/n/s

n lifetime in the trap is measured.

One measurement: 130 s filling;300 s storage; 130 s counting n’s

Magnetic field variation: 0.2 Gauss up/down

A.P. Serebrov et al, Experimental search for neutron–mirror neutron

oscillations using storage of ultra-cold neutrons (at ILL/Grenoble)

See also: Nuclear Instruments and Methods in Physics Research A 611 (2009) 137-140

Assuming zero mirror magnetic field oscillation time limit (90%CL) > 414 s

Bn n

(2008)

This is

“disappearance”

experiment

13

Eur.Phys.J. C72 (2012) 1974

Serebrov’s experiment (2008) was re-analyzed with treatment of 𝐵 ≠ 0

14

det ( ) ( )( )

( ) ( )B B

BB B

N t N tA t

N t N t

Measured asymmetry

~ (71.4)×104 (~5)

Magnetic anomaly in UCN trapping: signal for neutron oscillation to parallel world?

Z. Berezhiani and F. NestiEur. Phys. J. C72 (2012) 1974; also http://arxiv.org/abs/1203.1035

15

Experimental search for n n with UCN of another group

16

Attempt to find

resonance by

variation of mag.

field B

17

B

See: Z. Berezhiani and F. NestiEur. Phys. J. C72 (2012) 1974http://arxiv.org/abs/1203.1035

History of n lifetime

measurements,

PDG, 2014

Neutron Lifetime Measurements

18

9.2 s => ~ 3 σor <1% probability of statistical fluctuation

A.T. Yue, et. al., (UTK),887.7 ± 1.2 ± 1.9 s

Dewey, et. al., (NIST),886.8 ± 1.2 ± 3.2 s

Serebrov, et. al.,878.5 ± 0.7 ± 0.3 s

PDG Weighted Average

19

Particle Data Group (pdg.lbl.gov)

Two Methods of Neutron Lifetime Measurement

• Proton appearance detected

• 4.6 T magnetic field

• 10 ms storage

• Cold neutrons, ~0.025 eV

• Neutron disappearance detected

• 4 x 10-5 T magnetic field

• ~700 s storage

• Ultracold neutrons, ~ 62.3 neV

Beam Measurement Bottle Measurement

M. S. Dewey et al., Phys. Rev. Lett. 91, 152302 (2003); A. P. Serebrov et al., Phys. Rev. C 78, 035505 (2008). 20

at typical 𝐵 and 𝐵′

n'Mirror neutron has been resolved and will exit

Reflection from the wall

Via Oscillations nn’ Neutrons Can Interact with Mirror Particles

21

• Neutrons remain within the trap. Due to the oscillations between ordinary and mirror states, there is a small chance that the mirror neutron component will interact with an accumulated MM gas particle. (Z. Berezhiani, YK , B.Kerbikov, L. Varriano paper in preparation)

at typical 𝐵 and 𝐵′

n'Mirror neutron has been resolved and will exit

Reflection from the wall

oscP

22

in the beam of cold neutrons

n n ( )n n

Neutron total absorber

Neutron

detector

(neutron mirror neutron transformation) n n n

Z. Berezhiani, M. Frost, Y. K., B. Rybolt, “Neutron Regeneration from Sterile Mirror State”. Paper in preparation.

Search in the range of 𝜏 = 1 − 10 𝑠and scan for B = 0 0.5 Gauss

23M. Frost UT/SNS

Tube diameter 0.5 m

Neu

tro

ns

in d

etec

tor

/MW

s

B Field (mG)

Example scan in B with 𝜏 = 3, step ∆𝐵 = 5 𝑚𝐺

Assumes SNS neutron beam w/ 2x 15 meter pipe

B. Rybolt / UT

25

26

• UCN experiments at ILL indicated anomaly: neutron disappear from the trap for “no good reason”. 5 effect. Possible explanation: they disappear due to n noscillations to sterile mirror state with oscillation time 𝜏 ~3 𝑠 , if mirror magnetic field in the lab 𝐵~ 0.11 Gauss.

• Neutron lifetime measurements show difference in measurements by two methods: disappearance and appearance. > 3 effect. Can be explained by n n oscillations + presence of mirror matter in the UCN vacuum trap.

• New regeneration experiment can be made at SNS that can confirm/refute the observations made at ILL with UCN by different method. In the range of interest the counting rates are large. By scan with mag. field B the resonance in regeneration can be revealed proving not only that neutrons can transform to sterile (mirror) state, but also that mirror magnetic field exists.

• These observations can be a demonstration of Mirror nature of Dark Matter with profound significance for particle physics and cosmology.