CENAC MODEL WORKING GROUP’S REPORT

 

To teach ACCELERATORS students must have acquired some previous knowledge about:

 

P   Magnets and charges behavior

P   Electric field 

P   Forces / friction  / vectors

P   Energy (equations and units)

P   Movements (velocity and acceleration)

P   Electromagnetic induction

P   Atom’s constitution

P   History of the “Search for new particles”

 

After the teaching, they might go thoroughly into:

 

Magnetic properties of matter (atomic and nuclear magnetism) (optional)

Hall effect (measuring B with a probe) (optional)

Superconductivity (optional)

Simple relativistic approach (optional)

 

PHYSICS CONTENT

OBJECTIVES

Students must be able of…

PROPOSED     ACTIVITIES

The magnetic field B

How does a magnetic field can be created?

 

 

 

 

 

 

 

 

 

Magnitude order of different B

·  Define qualitatively B

·  To identify and draw lines patterns of a magnetic field  generated by a current

·  To establish the direction of a B applying Laplace law

·  Similarities and differences between B and E       

·  To measure B between the poles of an electromagnet

 

 

·     Distinguish among different order of magnitude for physical quantities

*  Simple electrical circuits to show Oersted law, relative movements of coils vs. current producing magnetic field or current

*  Repulsion/attraction between two parallel currents

*  Magnets attracting iron fillings / different patterns with long wire currents, solenoid, etc.

* Electromagnets characteristics

*Discharge in vaccum tubes (electron and cathode beams) deviated by a magnet

*To compare different magnetic field (table 1)

* To compare applications of different kind of accelerators (Table 2)

The magnetic force on a moving charge

Acceleration concepts

 

·  Define B as a vector and a quantity

·  Units and equations of B

·  To establish the relationship between B and E : ;

·  To explain why a magnetic force on a moving charge is much more complex than an electric force on a static charge

·  Units of energy (joule and electron-volt)

 

* Mathematical approach to B and definition of the Tesla

* Measuring different magnetic fields in the lab, including the Earth’s using a teslameter and/or a compass

*

 

 

 

 

 

 

PHYSICS CONTENT

OBJECTIVES

Students must be able of…

PROPOSED     ACTIVITIES

Accelerators concepts in particle physics research

 

 

 

 

 

 

 

 

 

 

Circulating charges

·  To define/calculate Lorenz force as the resultant force 

dp/dt  = F = Q*(E + v x B)

 

v = E/B

 

·        To understand and apply the relationship between v, B and F

 

·        To verify that:

P      Trajectory curvature only due to the B field

P      Energy gained only due to E field

 

·     To understanding that the deflecting force has two properties that affect the trajectories of charged particles responsible for their circular motion:

(1) it does not change the speed of the particles;

(2) it always acts perpendicular to the velocity of the particles

·                                            To understand and use the equations.,  

                          

                       

 

 

 

 

 

*Phill and Darren’s experiments

 

 

 

*Milikan’s experiment     or

*Modern version of Thompson’s experiment (e/m = 2yE/B2 L2) with Helmoltz Coils

 

*CDRom by Gillies, J. and Jacobson, R.

 

*Summarized translated parts of the following lectures, with the courtesy of:

-    Bruning, O.- Accelerators

-    Schmeling, S. – HEP experiments

-    Rossi, L. - Superconductivity

 

 

* Photos from different accelerators (Cyclotron, Synchroton), colliders, calorimeters, detectors, CERN, other research facilities to make the transition from classroom “teaching materials” to real life devices and events

 

 

 

TABLE 1: TYPICAL SIZES OF SOME MAGNETIC FIELDS (APPROXIMATE VALUES)

 

LOCATION

B (TESLA)

At the surface of a neutron star (calculated)

108

Near a superconducting magnet

5-10

Near a large electromagnet

1

Near a small bar magnet

10-2

At the Earth surface

10-4

In interstellar space

10-10

In the human brain

10-12

In a magnetically shielded room

10-14

In the human heart

10-15

 

 

 

 

 

 

TABLE 2 : APPLICATIONS OF ACCELERATORS IN OUR SOCIETY

 

APPLICATION  AREA

TYPE OF ACCELERATOR

Magnetic field magnitude/T

MEDICINE

 

 

INDUSTRY

 

 

GEOLOGY

 

 

RESEARCH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

COMPARISON BETWEEN RESULTS OBTAINED WITH THE CENAC AND RESEARCH DATA….

 

 

Variable

RESEARCH ACCELERATOR *

CENAC  MODEL  (USA)

Radius of the trajectory

3500 m

0,26 m

Length of the trajectory

27 000 m

1,63 m

Current ( I )

4 500 A

1,5 A

Resistance (R ) of the coil

 

8 W

Voltage difference

200 kV~

10-12 V -

Power (P ) dissipated

P > 39 GW (» 500 magnets)

P = 18 x 4 = 72 W (4 coils)

Friction (static))

Frictionless pipes

Fa = 1,6 x 10 –2 N

charge

Charged particles

No charge !!!

Particle sources

b-- (cathode rays    e-       )

 p+  (cathode tube with Hydrogen

anti-matter: pair production

An instantaneous “push” in the “ball bearing particle”

Mass

Massless /  electron and proton mass

2,026 x 10-3 kg

Time of one cycle

 

2.35 s (average) – 1,75 (min)

Speed

3 x 108 m/s

0,71 m/s (average) – 0,93 m/s (max.)

Acceleration

 

 

Kinetic energy

Particle global energy e = 0,51 MeV;

 p = 0,94 GeV

 

Magnetic Field

5 to 10 T

2,34 – 7,87 x 10-3 T