Presentation is loading. Please wait.

Presentation is loading. Please wait.

Fysikexperiment i forskning och samhälle, HT 2013.

Similar presentations


Presentation on theme: "Fysikexperiment i forskning och samhälle, HT 2013."— Presentation transcript:

1 Fysikexperiment i forskning och samhälle, HT 2013

2 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 What defines physics? What defines a physics experiment? Consider and discuss in groups the two questions above. Define a couple of points as answers to the questions.

3 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 The teachers’ answers What characterises physics? Striving for understanding and formulating the principal laws of nature Understanding the physical entities relevant for a physical system Understanding the nature of and interactions between these entities

4 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 What characterises a physics experiment? Control over cause – action Controlled conditions: Control of as many parameters as possible – systematic change of parameters Idealisation / Abstraction Reproducibility Fundament in theory and/or model Deliberate perturbation of a system in order to determine the system’s characteristics. Make the cause-study the action The teachers’ answers

5 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Boxes Think of physics experiments that could deliver information about the box and its contents. Which physical property would you like to determine? How would you determine this physical property? Why does your measurement allow measuring this particular physical property? What is the length scale of the physical property? What is the length scale of your experiment?

6 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Boxes Physical propertyProbeMeasured quantity mmµmnmpmfm

7 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Rutherford scattering

8 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Characteristics of a physics experiment Control over cause – action Controlled conditions: Control of as many parameters as possible – systematic change of parameters Idealisation / Abstraction Reproducibility Fundament in theory and/or model Deliberate perturbation of a system in order to determine the system’s characteristics Rutherford scattering vs Characteristics of physics experiments To what extent do these apply to the Rutherford scattering experiment?

9 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Probes In Out In Out

10 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Probes In Out Photons / Electromagnetic fields Electrons Atoms Ions Neutrons Protons Positrons Antiprotons Muons Pions Neutrinos...

11 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Choice of probe Determination of the properties: disturb by suitabe radiation Choose wavelength according to probed interaction Penetrate into (or emit from) interior or surface only? If you want to receive information on length scales: de Broglie wavelength = h/p of same order as (or smaller than) the structure studied Smaller structures … higher momentum … bigger machines Characterisation of a piece of matter: which properties are you interested in?

12 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 de Broglie wavelengths Wave- length P=E k if photonE k if electr.E k if p/n m ( m) 1.2keV/c (12keV/c) 1.4eV (140eV) Thermal m1.2MeV/c0.79MeV0.76keV m1.2GeV/c1.2GeV0.59GeV m1.2TeV/c1.2TeV

13 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Common concepts in experimental Physics Each group picks a concept from the list below. During the lectures the group identifies how this concept was relevant in the type of experimental studies that was covered in the lecture. You write a small essay about your concept in relation to the experimental physics you learn bout in the lectures. 2 pages written text plus figures. A preliminary writeup is delivered before the two last lectures. It is peer reviewed by your fellow who give feedbacktogether with one teacher. You respond to the criticism by correcting your text and include the two last lectures. Writing is individual, analysing the concept vs study material may be collaborative Concepts other years: Elastic scattering Inelastic scattering Energy levels Conservation rules (energy, momentum, charge..) Timing Excitation Quantal effects crossections

14 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Examples of spectroscopic measurements What do the following terms mean? Spectrum – Spectroscopy Where have you previously encountered these terms?

15 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Examples of spectroscopic measurements Spectrum = lat. apparition, appearance Came into use in the 17th century for describing what is seen when light is shone through a prism

16 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Examples of spectroscopic measurements X-ray photoelectron spectroscopy X-ray absorption spectroscopy Time-dependent x-ray photoelectron spectroscopy

17 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Nuclear probe on meteorite, x-rays Examples of spectroscopic measurements Almost Rutherford Gamma energies from 61 Zn 40 Ca + 24 Mg → 61 Zn +p+p+n+γ

18 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Particle spectroscopy at high energy Examples of spectroscopic measurements HEP: often P T instead of kinetic energy Early results from LHC (CMS exp) Masses are the quantal states

19 Lunds universitet / Fysiska institutionen / Fysikexperiment i forskning och samhälle FYSN11, HT 2009 Writing articles about physics Any text about physics should be properly referenced. You may quote other sources. But remember: Quotes must be marked clearly. You must always provide the reference of the source (even for internet texts!). Only an insignificant fraction of your text may be composed of literal quotes (i.e., no ”cut and paste”). Enough information should be provided that a reader can repeat the experiment


Download ppt "Fysikexperiment i forskning och samhälle, HT 2013."

Similar presentations


Ads by Google