POP

Danny Zhuang

LASER

FIBER STRETCHER

SENSOR

PHOTODIODE

AMPLIFIER

SPLIT

PXI-6221

PXI-6133

PXI-6221

RECOMBINEINTERFEREDBEAMS

FEEDBACK LOOP TO INPUT TO FIBER STRETCHER

CONVERTS LIGHT INTO VOLTAGE

SENSES DARK MATTER BUBBLE POPS

DISPLACES TO FIX THE PHASE DIFFERENCE BETWEEN THETWO BEAMS

RECORDS DM BUBBLE POPS

RECORDS IFPHASE

Life with LabView Text Based Programmer Week and a half

learning Began coding, learned

as I went ActiveX controls,

DAQmx Functions LabView source is very

messy (spaghetti code) Powerful GUI’s Excellent debugger

COUPP COUPP (Chicagoland Observatory for Underground Particle

Physics) 60 kg bubble chamber underground to avoid cosmic rays Works to detect Dark Matter; can detect Gamma rays,

neutrinos, muons, alpha, WIMPs, etc CF3I(Trifluoroiodomethane) sensitive to both spin-dependent

and spin-independent WIMP interactions Ideal temperature for each particle detection

Muon WIMPNeutron(s)

60°C 40°C40°C

SNOLAB Underground

physics Laboratory in Ontario, Canada (2km)

Specializes in neutrino and DM physics

Located in Vale Creighton Mine (Active Mine)

S- SudburyN- NeutrinoO- Observatory

The Job Highly sensitive

microphone Neutron vs. WIMP Neutron single scatter

sounds exactly like WIMP Multiple neutron scatter

is distinguishable Acoustic signature

differentiates Dark Matter nucleation

has a much higher acoustic sound

WIMP’s Weakly Interactive Massive Particles Could comprise of most if not all DM in

the universe React with weak force and gravity, no

electromagnetism, difficult to see, no strong force so do not react well with atomic nuclei

Shares properties with neutrinos except large mass thus slower and cold

Dark Matter

Matter inferred to exist because of gravitational effects on visible matter

Neither emits nor scatters light or other EM radiation

Would account for discrepancies between calculations of the mass of galaxies

So Why…

What we know about the world makes up only 4% of the universe

The other 96% is divided into two parts, Dark Energy and Dark Matter

The Old Bubble Chamber Charged Magnetic

field Particle Detector Particles

influenced by magnetic field

COUPP’s Bubble Chambers Revived technology of

particle physics Used to detect WIMPs Filled with superheated fluid

(CF3I) Depositing a small amount

of energy can nucleate the formation of an easily visible bubble

Effectively blind to the largest category of backgrounds

Progress in rejecting alpha recoils by using acoustic signature of bubble formation

When DM Passes Note: WIMP’s rarely interact with ordinary matter1. DM particle passes through bubble chamber2. Collides with a nuclei3. Elastic scatter, energy released4. Triggers evaporation of small amount of CF3I 5. Resulting bubble grows6. Digital cameras catch the process once bubble

reaches 1 mm in size7. Data stored for analysis However, the previous acoustic sensors were giving

off background radiation themselves, turned towards interferometry

Interferometry Family of techniques in which

electromagnetic waves are superimposed (place over) in order to extract information about the waves

Used in the fields of astronomy, fiber optics, engineering metrology, optical metrology, oceanography, seismology, quantum mechanics, nuclear/particle physics, plasma physics, remote sensing, and bimolecular interactions

Interferometers

Single beam is split them combined, halves travel different routes

Amplitude Splitting- primary wave is divided into two segments which travel different paths before recombining

Separate waves are combined to show some meaningful property that is diagnostic of the original state of the waves (superposition)

Routes cause a phase difference between the initially identical waves because of the unequal distances traveled by each beam

Quality of the interferometer depends on the positions of the mirrors being precisely stable

Interferometers cont’d 2 waves of same frequency combine and

result is determined by phase difference, decides constructive or destructive interference

1 crest 1 trough destructive interference (cancel)

2 crests constructive interference (add) Resulting total light field’s amplitude is sum of

amplitudes of superimposed beams Interference fringe- bands caused by beams of

light that are in phase or out of phase with one another

The Interferometer’s Role Interferometer-

instrument used to measure waves through interference patterns

Closed Laser, laser travels through optical fibers, laser couplers

Fibers detect the characteristic acoustic sound of a DM bubble nucleation

InterferenceTwo or more light beams superimposed•Spatial and temporal overlap of the two light fields•Coherence (fixed phase relationship between the electric field values at different locations or at different times) of the two light fields•Spatial coherence- a strong correlation (fixed phase relationship) between the electric fields at different locations across the beam profile, similar amplitudes•Temporal coherence means a strong correlation between the electric fields at one location but different times, tells how monochromatic a source is or how well it can interfere with itself

Astronomical Interferometry

Interferometers are ubiquitous

VLA (Very Large Array)- 27 telescopes giving 351 independent baselines at once, radio array

Mach-Zehnder Interferometer Used to determine relative phase

shift between two nearly parallel beams from a coherent light source

High coherence light from laser is split into reference and sensor arm then recombined

Photodetector measures combined light intensity

External influence (noise)

fiber couplers Instead of beamsplitters and fibersInstead of open source

Intro to Fiber Optics Optical fiber- thin, flexible fiber that acts as

a waveguide, transmitting light between the two ends of the fiber

Also used for illumination, wrapped in bundles

Immune to EM interference light goes through with few hindrances

compared to electrical cables (better) Wavelength division multiplexing (WDM)-

each fiber can carry many independent channels with light of different wavelengths

Multimode fibers- fibers that support many waves, efficient, cheaper

Single mode fibers- fibers that support a single wave, few hindrances

Good sensors for strain, temperature, pressure (DM sensor)

Laser Basics Laser emit amplified light

(electromagnetic radiation) with high spatial and temporal coherence

At higher temperatures, more current is needed to get the same power

Cold = more power Window between effective

output current and breaching max operating current is slim

Diode- semiconductor with 2 terminals, flows one way

Hardware: Building the Interferometer

Wavelength stabilized single mode fiber coupled laser diode 5mW of 1300nm

(wavelength) -infrared Low threshold current

and high slope efficiency

Operating temperature range: -40ºC 50ºC

Built-in monitor photodiode, thermo-electric cooler, and thermistor

LASER

SPLIT

Optiphase PZ1 Fiber wound piezoelectric element (transfers

electrical to mechanical) Takes in voltage, displaces the optical fiber to

get rid of phase differences between 2 beams High-speed fiber stretcher

Sensor

Optical Fibers Picks up noise

LASER

FIBER STRETCHER

SENSOR

SPLIT RECOMBINEINTERFEREDBEAMS

SENSES DARK MATTER BUBBLE POPS

DISPLACES TO FIX THE PHASE DIFFERENCE BETWEEN THETWO BEAMS

InGaAs Fixed Gain Detector Used to convert

light into voltage 700-1800 nm

(infrared) 150 MHz BW Amplified

photodetector

LASER

FIBER STRETCHER

SENSOR

PHOTODIODE

SPLIT RECOMBINEINTERFEREDBEAMS

CONVERTS LIGHT INTO VOLTAGE

SENSES DARK MATTER BUBBLE POPS

DISPLACES TO FIX THE PHASE DIFFERENCE BETWEEN THETWO BEAMS

T-Cube Laser Diode Controller

T-Cube TEC Controller

PXI-6221 Capable of both Analog

Input and Analog Output (ideal for the feedback loop to the Fiber Stretcher)

Slower than 6133 (250k samples per second)

PXI-6133 Only Capable of

Analog Input 10 times faster

than 6221 (2.5M samples per second)

LASER

FIBER STRETCHER

SENSOR

PHOTODIODE

AMPLIFIER

SPLIT

PXI-6133

PXI-6221

RECOMBINEINTERFEREDBEAMS

CONVERTS LIGHT INTO VOLTAGE

SENSES DARK MATTER BUBBLE POPS

DISPLACES TO FIX THE PHASE DIFFERENCE BETWEEN THETWO BEAMS

RECORDS DM BUBBLE POPS

RECORDS IFPHASE

PID Controller Proportional-Integral-Derivative (PID) control is the most

common control algorithm used in industry and has been universally accepted in industrial control

generic control loop feedback mechanism used in industrial control systems

Attempts to minimize error by adjusting process control inputs

PID feedback loop fixes the phase difference between the two beams and keeps the ideal fringe (light/dark; constructive/destructive)

PID Controls P- Proportional (Kp) I- Integral (Ki) D- Derivative (Kd)

The “Car” Analogy A car’s cruise

control is a PID Controller

PID Theory P Response- determines ratio of output

response to error signal controls the speed of the control system response depends on error (set point – process variable) can cause process variable to oscillate and system to

become unstable I Response- sums error over time (past error)

increases more as the error term increases D Response- predicts future error

causes output to decrease if process variable is increasing rapidly

increases with rate of change very sensitive to noise

PID Equation

U(t) = controller output MV(t)= manipulated variable Kp= proportional gain, constant Ki = Integral gain, constant Kd = Derivative gain, constant E = error (Set Point – Process Variable) T = Time

Terminology

LASER

FIBER STRETCHER

SENSOR

PHOTODIODE

AMPLIFIER

SPLIT

PXI-6221

PXI-6133

PXI-6221

RECOMBINEINTERFEREDBEAMS

FEEDBACK LOOP TO INPUT TO FIBER STRETCHER

CONVERTS LIGHT INTO VOLTAGE

SENSES DARK MATTER BUBBLE POPS

DISPLACES TO FIX THE PHASE DIFFERENCE BETWEEN THETWO BEAMS

RECORDS DM BUBBLE POPS

RECORDS IFPHASE

School

Applied science jumpstart to career and prepare for the real world

Principles and the laws of science are applicable to many things

Ability to do specialized and targeted research goes a long way

Computer Programming Awareness Growing industry Useful in almost

any job field In high demand Creativity FUN

To the Next Group of Victims and Scientists

VI readme for all programs My deepest regrets Advice document listing useful

tutorials, articles, websites, etc. My programs

Special Thanks Jeter Hall- Mentor, teacher, and

companion Supervisors Julia Dawson & Fritz

Dejongh