what are cosmic rays?
Post on 31-Jan-2016
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What are Cosmic Rays?What are Cosmic Rays?
Particles bombarding Earth from outer Particles bombarding Earth from outer spacespace
Includes protons up to heavy elementsIncludes protons up to heavy elements Ionic charge and energy vary greatlyIonic charge and energy vary greatly
Cosmic Ray DetectorCosmic Ray Detector
Jason AliceaJason Alicea
University of FloridaUniversity of Florida
Dr. Muga Dr. Muga
Nuclear Chemistry Dept.Nuclear Chemistry Dept.
OutlineOutline
Detector overviewDetector overview What I didWhat I did• Detector testDetector test• Scattering chamber designScattering chamber design
Conclusion-What next?Conclusion-What next? Questions?Questions?
Cosmic Ray Detector Measures...Cosmic Ray Detector Measures...
Nuclear charge (Z)Nuclear charge (Z) EnergyEnergy VelocityVelocity MassMass Ionic chargeIonic charge
Detector ComponentsDetector Components
Thin film detector (TFD, measures Thin film detector (TFD, measures luminescence)luminescence)• Thin scintillator filmThin scintillator film• Photomultiplier tubesPhotomultiplier tubes
Solid state detector (SSD, measures Solid state detector (SSD, measures energy)energy)
SSDSSDParticlesParticles
Photomultiplier tubesPhotomultiplier tubes
Thin filmThin film
Why Measure Luminescence?Why Measure Luminescence?
Luminescence-Energy curves are Luminescence-Energy curves are unique for each atomic number Z.unique for each atomic number Z.
ZZ
ZZ
ZZ
11
22
33
EnergyEnergy
Lum
ines
cenc
eLu
min
esce
nce
ZZ
ZZ
ZZ
11
22
33
EnergyEnergy
Lum
ines
cenc
eLu
min
esce
nce
Data PointData Point
Atomic # ofAtomic # of ParticleParticle
Atomic number of particle corresponds Atomic number of particle corresponds to the curve data point lies on.to the curve data point lies on.
Why Measure Luminescence?Why Measure Luminescence?
What About Other 3 Properties?What About Other 3 Properties?
Velocity: divide distance between thin Velocity: divide distance between thin film and SSD by time recorded between film and SSD by time recorded between signalssignals
From measured energy & velocity, From measured energy & velocity, mass is easily calculatedmass is easily calculated
Ionic charge: compare luminescence & Ionic charge: compare luminescence & velocity after each of several thin filmsvelocity after each of several thin films
What Did I Do?What Did I Do?
Fabricated a thin film, which was used Fabricated a thin film, which was used in testing the detector.in testing the detector.
Recorded response of thin film and Recorded response of thin film and SSD to fission fragmentsSSD to fission fragments
Designed scattering chamberDesigned scattering chamber
Detector TestDetector Test
Used newly fabricated thin filmUsed newly fabricated thin film Test particles were californium (Cf) Test particles were californium (Cf)
fission fragmentsfission fragments Measured response from thin film and Measured response from thin film and
solid state detector.solid state detector. Computer recorded luminescence and Computer recorded luminescence and
energy data.energy data.
Solid State Detector ResponseSolid State Detector Response
0
4
8
12
16
20
1 18 35 52 69 86 103 120 137 154 171 188 205 222 239 256
Energy
Co
un
ts
Good signal since peak is narrow.Good signal since peak is narrow.
0
4
8
12
16
20
1 18 35 52 69 86 103 120 137 154 171 188 205 222 239 256
Luminescence
Co
un
ts
Thin Film ResponseThin Film Response
Peak is too wide--results in Peak is too wide--results in uncertainty in Z determinationuncertainty in Z determination
Scattering Chamber: Why?Scattering Chamber: Why?
Beam from Van de Graaff accelerator is Beam from Van de Graaff accelerator is too strong for SSD and electronicstoo strong for SSD and electronics
SSD can be damaged and electronics SSD can be damaged and electronics overloadedoverloaded
By scattering the beam off a foil By scattering the beam off a foil (Rutherford scattering), intensity will be (Rutherford scattering), intensity will be adequately reducedadequately reduced
Design RequirementsDesign Requirements
Scatter through angles between 0 and Scatter through angles between 0 and 60 degrees60 degrees
Chamber must accommodate at least 3 Chamber must accommodate at least 3 scattering foilsscattering foils
Must be kept at vacuum pressure Must be kept at vacuum pressure
Final DesignFinal DesignPlunger to raise/Plunger to raise/lower foilslower foils
FixedFixedCylinderCylinder
Scattering Foils (5)Scattering Foils (5)Beam Pipe to Beam Pipe to DetectorDetector
Beam Pipe toBeam Pipe toAcceleratorAccelerator
Rotating Rotating CollarCollar
What Next?What Next?
Improvements are underway to Improvements are underway to strengthen thin film signalstrengthen thin film signal• Copper thin film?Copper thin film?
Design of scattering chamber is Design of scattering chamber is complete, construction is anticipatedcomplete, construction is anticipated
If perfected, detector would be an If perfected, detector would be an excellent candidate for a space mission, excellent candidate for a space mission, which is the ultimate goal.which is the ultimate goal.
Questions?Questions?
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