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Dark Matter : An Opportunity for Discovery. By: Francisco Gonzalez, Veronica Hernandez, Fernanda Torres, and Israel Vega Instructors: Julie A. Rolla, Nathan Earnest, and Arran Phipps Primary Investigator: Bernard Sadoulet. Overview:. What is Dark Matter?
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Dark Matter: An Opportunity for Discovery By: Francisco Gonzalez, Veronica Hernandez, Fernanda Torres, and Israel Vega Instructors: Julie A. Rolla, Nathan Earnest, and Arran Phipps Primary Investigator: Bernard Sadoulet
Overview: • What is Dark Matter? • A theory to answer the question of what is the universe made of? • Types of forces • Weak Force • Strong Force • Electromagnetic • Gravity • Radiation • Types • Alpha • Beta • Gamma • Detectors • Photomultiplier Tubes • Ge and Si detectors • The Cloud Chamber: • Temperature Gradient • Condensation trails
What is Dark Matter? • A theory of what may be in the space between stars, planets, galaxies etc. • Discovered by Fritz Zwiky in the 1930s • Thought to be composed of WIMPs (Weakly Interacting Massive Particles) • Five times as heavy as stars, planets, asteroids and all other known matter Unknown Universe- 75% Known Universe- 5% Dark Matter (only a theory)- 20%
Forces: Electromagnetism: When two charges attract or repel each other. Strong Force: It binds the nucleus together. Gravity: It causes two particles to pull together. Weak Force: Is like electromagnetism, but much weaker. http://www.particlephysics.ac.uk/explore/the-standard-model.html
Interactions/Proof: Dark Matter has not been directly detected, but many scientists can tell when dark matter is in a certain place because it affects the movement of galaxies, stars, etc. • Spiral galaxies should be expandig • but something is keeping them • together • It has gravity • Dark Matter bends light, • making it seem as if there is • a galaxy in two different places, • but there is only one • "Bullet Cluster"- Dark Matter went right through each other because there is no electromagnetism, but regular matter collided. http://chandra.harvard.edu/photo/2006/1e0657/ http://www.phdcomics.com/comics.php?f=1430 http://www.learner.org/courses/physics/unit/text.html?unit=10&secNum=4
Radiation: • Alpha Radiation- these are fast moving helium • nuclei • Large mass, high energy • Are stopped by a few inches of air or a piece • of paper • Beta Radiation- these are fast moving electrons • Less massive than helium atoms • Can penetrate through several feet of air or millimeters of plastic/light metal • Gamma Radiation- these are photons. • Typically higher energy than visible light • Depending on energy level, they can be stopped by a thin piece of aluminum foil or a few inches of lead http://www.deq.idaho.gov/inl-oversight/radiation.aspx
Radiation Detectors: • Photomultiplier Tubes • Super sensitive tubes that detect light • They re-produce the light they detect by as much as 100 million times • Germanium or Silicon Detectors • Absorb light into E-tubes • The detectors are semiconductors- that means that it only conducts in perfect conditions. (the colder the working environment the better the conductor. http://en.wikipedia.org/wiki/Photomultiplier
Cloud Chamber: Cloud chambers- • Original method of detecting invisible particles going through the atmosphere. • It can't detect WIMPS. • WIMPs make up dark matter. • A heat gradient from the top of the chamber to the bottom of the chamber causes the alcohol in the chamber to be super saturated. • Gradient- Change of something over a distance. • Cloud Condensation Nuclei (CCN) • Gas molecule want something to condense onto. • An invisible particle enters (Cloud Condensation Nuclei). • A trail of condense vapor is formed, following the particle.
Conclusion Dark matter does not interact through any forces but can be detected using other methods. • Types of forces • Weak Force • Strong Force • Electromagnetism • Gravity • There are a a few ways in which scientists have proven the existence of dark matter. Some of these ways are: • "Bullet Cluster" • Two galaxies collided into each other and the normal matter slammed into each other, but the dark matter passed right through each other. • Gravity's affect on light • When dark matter interferes with the light, the dark matter bends it. • Things don't Spin the way they should • Stars are being held together even though they are spinning super fast In addition to dark matter, there is still much more out there waiting to be discovered.