Fall 2013 Eugene V. Colla - University Of Illinois · dB. Physics 401 Spring 2013 5 dl a r dB q dB z I z (0,0,z 1) a dl x z r q dB dB z q z1 d ... – 2nd sound in He4 superfluid

Fall 2013

Eugene V. Colla

Physics 401 Spring 2013 2

The main goals of the Lab:

Study of the magnetic field distribution created by

various systems using Hall probe and Gauss meter.

Calculating for simple systems the magnetic field

profile and comparing it with experimental data.

Getting understanding of the application of the Hall

effect to measurements of the magnetic fields.

This is one week Lab


Magnetic field due to current loops

Helmholtz coils

Solenoid

Halbach magnets

Hall effect. Measuring of the magnetic field


Jean-Baptiste Biot

(1774-1862)

Félix Savart

(1791-1841)

dl

I34

o Idl rdB

r

0 410-7 N/A2,

permeability of the

free space

dB

http://upload.wikimedia.org/wikipedia/commons/6/6c/Jbiot.jpg

http://upload.wikimedia.org/wikipedia/commons/6/6c/Jbiot.jpg


dl

a

r

dBdBzq

I

z

(0,0,z1)

a

dl

x

z

r

qdB dBz

q

z1

dl a d

df

cosz

adB dB dB

rq

2

0

34

z

a ddB

r

2

0

3

2 2

0 0

3 3

2 2 21

4

2 2

z z

I aB dB d

r

I Ia a

rz a


Hermann Ludwig

Ferdinand von

Helmholtz

(1821-1894)

Magnetic field vector in a plane

bisecting the current loops.

(courtesy Wikipedia)

http://upload.wikimedia.org/wikipedia/commons/0/01/B_vector.helmholtz.svg

http://upload.wikimedia.org/wikipedia/commons/0/01/B_vector.helmholtz.svg


I I

z

N turns

0

a

a

2

0

32 2 21

2

I aB z

z a

For single loop:

For Helmholtz coils total current equals NI,

2

az z For right hand coil and

2

az z for left hand coil

B

Modern Experimental PhysicsIntroduction for Physics 401 students

Fall 2013

Eugene V. Colla

• Goals of the course

• Experiments

• Teamwork

• Schedule and assignments

• Your working mode

9Physics 401 Spring 2013

10

• Primary: Learn how to “do” research

Each project is a mini-research effort

How are experiments actually carried out

Use of modern tools and modern analysis and data-recording techniques

Learn how to document your work

• Secondary: Learn some modern physics

Many experiments were once Nobel-prize-worthy efforts

They touch on important themes in the development of modern physics

Some will provide the insight to understand advanced courses

Some are just too new to be discussed in textbooks

Physics 401 Spring 2013

11

Primary. Each project is a mini-research effort

Step1. Preparing:• Sample preparation• Wiring the setup• Testing electronics

Preparing the samples for ferroelectric measurements

Courtesy of Emily Zarndt & Mike Skulski (F11)

Step2. Taking data:If problems – go back to

Step 1.

Standing waves

resonances in Second

Sound experiment

Courtesy of Mae Hwee Teo and

Vernie Redmon (F11)


12

Primary. Each project is a mini-research effort

Step3. Data Analysis If data is “bad” or not

enough data point – go back to Step 2

Step4. Writing report and preparing the talk

Plot of coincidence rate for

22Na against the angle between

detectors A and B. The fit is a

Gaussian function centred at

179.30° with a full width at half

maximum (FWHM) of 14.75°.

Courtesy of Bi Ran and Thomas

Woodroof

Author#1 and

Author#2


Primary. How are experiments actually carried out ?

The procedures are not all written out

The questions are not in the back of the

chapter

The answers are not in the back of the book

You will have to learn to guide your own activities


Primary. Use of modern tools and modern analysis and data-recording techniques

• Lock-in amplifiers

• Digital scopes

• Precise DMM’s

• Multichannel analyzers

• Cryogenic equipment

• Temperature controllers

• Sample preparation equipment

• Microscopse

• Modern optical equipment

• etc.


Primary. Learn how to document your work

On line. Electronic logbook

Making an analysis report,Writing formal report

Presenting your findings orally


Many experiments were once Nobel-prize-worthy efforts

1913. Heike Kamerlingh

Onnes

"for his investigations on

the properties of matter at

low temperatures which led,

inter alia, to the production

of liquid helium".

1973. Ivar Giaever

"for their experimental discoveries

regarding tunneling phenomena in

semiconductors and

superconductors, respectively"

1976. Pyotr Leonidovich

Kapitsa

"for his basic inventions and

discoveries in the area of

low-temperature physics"

1986. Gerd Binnig

"for their design of

the scanning

tunneling

microscope"

1952. Felix Bloch and Edward Mills Purcell

"for their

development of

new methods for

nuclear magnetic

precision

measurements and

discoveries in

connection

therewith"

16

Secondary: Learn some modern physics


All experiments are divided in three main groups: Condensed Matter (CM),

Nuclear/ Particle Physics (NP), Atomic/Molecular/Optics (AMO)

• Condensed Matter (CM)– Superconductivity

– Tunneling in superconductors - new

– Contactless detecting of the superconductivity. Penetration depth.

– 2nd sound in He4 superfluid state

– Ferroelectrics and ferroelectric phase transition. Dielectric and pyroelectric study (Ferro1)

– Optical Investigation of the ferroelectric phase transition and domain formation (Ferro2)

– Polarization of the ferroelectrics. Hysteresis loops (Ferro3) –new

– Low temperature thermometry. Sensors calibration.

– Pulsed NMR

– Special Tools:

• Vacuum film deposition

• Atomic Force Microscope

• Polarizing microscope


• Nuclear / Particle (NP)– Alpha particle range in gasses

– Cosmic ray muons:

– Angular correlations in nuclear decay

– Angular distribution of cosmic rays

• Atomic / Molecular / Optics (AMO)– Optical pumping of rubidium gas

– Berry’s phase

– Quantum erasure

– Quantum Entanglement

– Florescence spectroscopy


Ferro1

Samples on the cryostat

stage

(1)

Sample preparation

setup150 200 250 300 350 400 450 5000

3

6

9100Hz

T (K)

'/1

000

1K/min

(2)

(3)

Results:

Temperature

dependence of the

dielectric constant

of barium titanate


Ferro2

Courtesy of Dave Grych and Thomas

Hymel (F10)

Setup

Domains in tetragonal phase of BaTO3

Idea of operating


Transmitter

Receiver

To lock-in

L

R1

R2

T<2.17KIdea of the experiment

0 100 200 300 400 500 600 700 800 9000.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

40 50 60 70

0.25

0.50

0.75

T = 1.57K

ƒ (Hz)

R

V

R

V

Raw dataFinal result

Second sound


Muon counting

Main stock of scintillators

Wiring Courtesy of Deniz Köksal, Emily Zarndt

Muons precession in magnetic field


Optical pumping

5.14 5.16 5.18 5.20 5.22 5.24 5.26 5.28

0.44

0.46

0.48

0.50

0.52

Inte

nsit

y (

a.u

.)

f (MHz)

Energy transitions of Rb85 for 10.8 G.

Double quantum transitions can be seen

and occur when two photons are

simultaneously absorbed. Courtesy of Natasha

Sachdeva (S2011)

85Rb


24

An example of Lab manual

• Many are just guides

• A few purchased experiments have “real” manuals

• We serve as your guides … like real research


25

Item Points

Expt. documentation: elog reports, shift summaries, plot quality; paper logbooks

180 Total

60 / cycle

Formal reports: physics case, quality of results, depth of analysis, conclusions

600 Total

100 / report

Oral reports: motivation, organization of presentation; fielding questions

225

75 / oral

Total

Effective point total will be

1005

1000 grade




• Total 18-20(?) seats

• The course is more appropriate for juniors and

seniors

• Prerequisite: Credit or concurrent registration in

PHYS 486.

• Instructor Approval Required


Documents

Fall 2013 Eugene V. Colla - University Of Illinois · dB. Physics 401 Spring 2013 5 dl a r dB q dB z I z (0,0,z 1) a dl x z r q dB dB z q z1 d ... – 2nd sound in He4 superfluid