I.Laktineh, IPNL 1 Nagoya, 2006 Studying the neutron quantum states in the gravitational field “using nuclear emulsion technique” Motivations Motivations

I.Laktineh, IPNLI.Laktineh, IPNL 11Nagoya, 2006Nagoya, 2006

Studying the neutron quantum Studying the neutron quantum states states

in the gravitational fieldin the gravitational field“using nuclear emulsion technique”“using nuclear emulsion technique”

• MotivationsMotivations

• Results obtained with CR39Results obtained with CR39

• Perspectives with emulsionPerspectives with emulsion

Nagoya, 2006Nagoya, 2006 I.Laktineh, IPNLI.Laktineh, IPNL 22

"Let us consider another possibility, an atom held together by gravityalone. For exemple, we might have two neutrons in a bound state. When we calculate the Bohr radius of such an atom, we find that it would be 108 light years, and that the atomic binding energy would be 10-70 Rydbergs. There is then little hope of ever observing gravitational effects on systems which are simple enough to be calculable in quantum mechanics."

Brian Hatfield, in "Feynman Lectures on Gravitation" ;R.P. Feynman, F.B. Morinigo, W.G. Wagner, Ed. Brian Hatfield

Addison-Wesley Publishing Company, 1995, p. 11


Neutrons in gravitational Neutrons in gravitational fieldfield

1,41

2,46

3,32

0 14 24 32 ,z m

,nE peV( )V z mgz

2

30 2

5,87 m2

zgm

2

qc 39 1

8 4

n

mE g n

Academic exercise


Some historySome history• Solution of Schrödinger equation with linear potential Solution of Schrödinger equation with linear potential 19281928 : :

G. Breit, G. Breit, Phys RevPhys Rev 3232 (1928) 273 (1928) 273

• First attempts of First attempts of ultra coldultra cold neutron storage at JINR (Dubna) in neutron storage at JINR (Dubna) in 19681968 : :

V.I. Luschikov et al., V.I. Luschikov et al., JETP LettJETP Lett 9 9 (1969) 40(1969) 40

• 19761976, proposal to look for quantum energy levels using ultra , proposal to look for quantum energy levels using ultra old neutrons :old neutrons :

V.I. Luschikov, V.I. Luschikov, Physics TodayPhysics Today 42 42 (1977) 51;(1977) 51;

V.I. Luschikov and A.I. Frank, V.I. Luschikov and A.I. Frank, JETP LettJETP Lett 28 28 (1978) 559(1978) 559

• First observations of the quantum states in a gravitational First observations of the quantum states in a gravitational field at field at ILL/France ILL/France in in 19991999 : :

V.V.NesvizhevskyV.V.Nesvizhevsky et al., et al., NatureNature 415415 (2002) 297; (2002) 297;

Phys RevPhys Rev D87D87 (2003) 102002 (2003) 102002


Institut Laue Langevin, Institut Laue Langevin, Grenoble/FranceGrenoble/France

ILL

ESRF

LPSC/IN2P3

100 km from Lyon


requirementsrequirementsTo observe quantum states in gravitational fieldTo observe quantum states in gravitational field- neutral particle- neutral particle- long lifetime long lifetime ultracold ultracold neutron neutron - small mass - small mass (E<2 µeV, V<6 m/s) (E<2 µeV, V<6 m/s) - weak energy (very low temperature)- weak energy (very low temperature)

A well provided byA well provided by -a -a mirror mirror with:with:

- elastic diffusion at least 99,99%- elastic diffusion at least 99,99%- absorption 10- absorption 10-5 -5 negligible negligible

vertical vertical - inelastic diffusion < 10- inelastic diffusion < 10-4 -4

speedspeed

-a -a gravitational fieldgravitational field


Experiment setupExperiment setup

ADC

DAC

Amplifier

Amplifier

Shuttercontrol

COMPUTER

11

10 98

765

4

3

2

1

1. Neutron guide2. Anti-vibration table3. Polished granite stone4. Piezo translators5. Vacuum chamber6. Mirrors and absorber7. Detector8. Anti-magnetic shielding9. Input collimator10. Neutron shutter11. Inclinometers

10 cm

Vh =fewm/s

Vv=fewmm/s

x


DetectorDetector

Plastic

Uranium-235

Supermirror coatingFission

fragment

X

UCNneutrons

~0.2 m ~0.5 m

120 mm

Picture of developed detector with tracks

15 m

m


Neutrons in gravitational Neutrons in gravitational fieldfield

1,41

2,46

3,32

0 14 24 32 ,z m

,nE peV( )V z mgz

2

30 2

5,87 m2

zgm

2

qc 39 1

8 4

n

mE g n

Academic exercise


Wave functionWave function

0 10 20 30 40 50Z, micron

1st quantum state

0 10 20 30 40 50Z, micron

2nd quantum state

0 10 20 30 40 50Z, micron

3rd quantum state

0 10 20 30 40 50Z, micron

4th quantum state

2 ( )n z


ProcedureProcedureAfter the exposure to the UCN beam one has to

- take out the Uranium (U235) layer- itch the CR39 to produce the tracks- scan the CR39

The observation of the quantum states of neutrons in gravitational field can then be obtained by “visualizing” the square wave function moduleusing the neutron impact density.

Many problems were to be addressed:-The Z zero position should be determined for the whole CR39 plate-The mechanics precision should be less than 1

But Itching leads to the CR39 curvature as well as scratches…


Etching of uranium coating

The etching may curve the detector in following manner:

For this reason reference lines were used to estimate the curvature


First resultsFirst results

Nesvizhevsky et al.,J. Phys. C40 (2005)

479

Results obtainedby semi automatic scannig


What the automatic scanning can What the automatic scanning can provide?provide?

The semi-automatic scanning suffers from some The semi-automatic scanning suffers from some drawbacksdrawbacks

1)1) It lasts about two months for each plate leading to It lasts about two months for each plate leading to uncertainties on the absolute position due to uncertainties on the absolute position due to temperature and mechanics temperature and mechanics

2)2) Human intervention introduces subjective decisions Human intervention introduces subjective decisions which thus differ from one operator to another. which thus differ from one operator to another.

3)3) CR39 degradation with time if not properly CR39 degradation with time if not properly protectedprotected



At the French Scanning station we adapted the ESS At the French Scanning station we adapted the ESS to scan some of the exposed CR39.to scan some of the exposed CR39.

• The tracks are limited to the surface with a The tracks are limited to the surface with a maximum penetration of 10 microns. maximum penetration of 10 microns.

12-15 tomographic layers were used 12-15 tomographic layers were used 1h/plate. 1h/plate.• All the tracks were found except those of large angleAll the tracks were found except those of large angle (tg (tg > 5) > 5)• Scratches dues to itching process simulated fake Scratches dues to itching process simulated fake

tracks tracks “ “however automatic scanning can be controlled easily however automatic scanning can be controlled easily

and quickly by a manual scanning”and quickly by a manual scanning”



In 2007-2008 a new run with more statistics is expectedIn 2007-2008 a new run with more statistics is expected• CR39 is a good detector but its relatively bad surface CR39 is a good detector but its relatively bad surface

planarity and the scratches left by the Uranium itching planarity and the scratches left by the Uranium itching convince us to try to use emulsion. However emulsion convince us to try to use emulsion. However emulsion density is about twice the CR39 one ( 3 vs 1.3) which density is about twice the CR39 one ( 3 vs 1.3) which means that ions will produce very short tracks means that ions will produce very short tracks

(< 5 microns) which are hard to work out.(< 5 microns) which are hard to work out.• Diluted emulsion of 20-30 microns thickness can be Diluted emulsion of 20-30 microns thickness can be

of great help. Indeed the tracks can be seen from the of great help. Indeed the tracks can be seen from the side opposite to the U235 covered side limiting the side opposite to the U235 covered side limiting the scratches scratches

effects effects • In both cases tracking algorithms capable of finding In both cases tracking algorithms capable of finding

horizontal tracks are on preparation. horizontal tracks are on preparation.


ConclusionConclusion

• The automatic scanning development we engaged for OPERA can be a wonderful tool for amazing and very interesting application. • Ultra cold neutrons is one of those topics that our scanning system can perform with negligible systematics. (quantum states, 5th force search, axions…) • The emulsion can be a competitive and even better one but we need help from our Japanese colleagues.

Documents

I.Laktineh, IPNL 1 Nagoya, 2006 Studying the neutron quantum states in the gravitational field “using nuclear emulsion technique” Motivations Motivations