Large Bulk Matter Search for Fractional Charge Particles I. T Lee, - - PowerPoint PPT Presentation

Fractional Charge Search

Large Bulk Matter Search for Fractional Charge Particles

• I. T Lee, S. Fan, V. Halyo, E. R. Lee, P

. C. Kim, M. L. Perl, and H. Rogers SLAC

• D. Loomba

University of New Mexico

• K. S. Lackner

Columbia University

• G. Shaw

University of California-Irvine

Fractional Charge Search

Research Interests

• Free particles with fractional electric charge (FCPs)

These could be unbound quarks, non-integer charged bound states of quarks, leptons with non-integer charge, or more exotic particles

• Very massive stable particles

These particles would have masses greater than

1 TeV, which are unreachable using current accelerator facilities

Small scale, tabletop experiments

Fractional Charge Search

Outline

• Motivation
• Millikan’s Technique
• Apparatus
• Software
• Analysis
• Future Plans

Fractional Charge Search

Background

• Search Techniques

– Accelerator – Cosmic rays – Levitometer – Millikan

• Implications of null result

– Extremely rare – May have high mass – Unpredictable distribution

Fractional Charge Search

FCP Candidates

• Free quarks

Is confinement absolute? Is it possible for primordial free quarks produced during the early universe to still exist today?

• Particles from beyond the Standard Model

FCPs are a generic feature of theoretical physics beyond the Standard Model. Typically, mechanisms must be invented to eliminate these particles from

• bservation.
• Dark Matter

Recent papers have shown that it is possible for dark matter to be composed of fundamental charged particles (CHAMPS).

Fractional Charge Search

Bulk Matter Searches

Group Material Technique Mass (mg)

LaRue et al. (1981) Niobium Levitometer 1.1 0.010–0.093 Marinelli et al. (1982) Iron Levitometer 3.7 0.013–0.129 Liebowitz et al. (1983) Iron Levitometer 0.72

Smith et al. (1985) Niobium Levitometer 4.87 0.02–0.05 Jones et al. (1989) Meteorite Levitometer 2.8 0.03–0.07 Hodges et al. (1981) Mercury Millikan 0.6 0.035–0.040 Joyce et al. (1983) Sea Water Millikan 0.05 0.037 Lindgren et al. (1983) Mercury Millikan 0.5 0.035 Savage et al. (1986) Mercury Millikan 2.0 0.040 Mar et al. (1996) Silicone Oil Millikan 1.07 0.025 Halyo et al. (2000) Silicone Oil Millikan 17.4 0.020

Fractional Charge Search

Millikan’s Method

Detection of FCPs in fluid samples via direct measurement of their charge, using Stokes’s Law.

• Based on simple, well understood physical principles
• Easily automatable for high throughput
• Large statistics allow for self-calibration, reducing the

possibility of artifacts

• Able to test any material which can be suspended in

a liquid

• No limitation on the charge of the FCP

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Experimental Principle

x z

Airflow Duct Falling Drop Field Plate Electric High Voltage Laminar Air Flow

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Operating Point

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Throughput Limitations

Charge accuracy must be acceptable!

• Number of independant charge measurements
• Brownian motion
• Centroiding error
• Charge distribution of drops
• Collisions between drops
• Drop to drop coupling through fluid dynamic

interactions in the air

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Apparatus

Camera Microdrop Ejector Electric Field Plate Z Y X Entrance Tube for Air Transparent Walls CCD Lens Transparent Outer Chamber Strobed LED Array Airflow Duct

Fractional Charge Search

Apparatus

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Drop on Demand Fluid Ejector

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Airflow Tube

The airflow profile across the chamber cross section is determined by the solution to Poisson’s equation.

3.12 cm 0.83 cm

• 3
• 2
• 1

1 2 3 0.2 0.4 0.6 0.8 1

Fractional Charge Search

Airflow System

Fractional Charge Search

E Field Plates

Fractional Charge Search

Apparatus

Camera Microdrop Ejector Electric Field Plate Z Y X Entrance Tube for Air Transparent Walls CCD Lens Transparent Outer Chamber Strobed LED Array Airflow Duct

Fractional Charge Search

Electronics

1 s 1 s

CCD Camera Frequency Divider HV Power Supply Electric Field Plates LED Driver High Voltage Switcher Computer Pulse Generator HV Pulse Amplifier Drop Generator Data Storage LED Light Source

+V −V Field Index HV Monitor Sparse Data 10 Hz Clock Image Data

E Field LED Pulses

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Software Tasks

• Data acquisition
• Image processing
• Pattern recognition
• Analysis and diagnostics

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Computing

• Data Acquisition Machines

– High speed digital framegrabber – A/D Input/Output board – Linux drivers for hardware – Data acquisition software

• Analysis Machines

– CD/DVD recorder – Analysis software

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Image Processing

• ✫

Fractional Charge Search

Tracking Algorithm

• For every drop, predict the position of the

next centroid.

• Look for the predicted centroids in the most

recent image.

• If there is a unique match, associate the

centroid with the drop.

• If the drop leaves the field of view or does not

have a unique match, the drop is terminated and is passed on to analysis.

• Consider all possible combinations of the

remaining centroids to acquire new drops.

Fractional Charge Search

Tracking Algorithm

The problem to be solved

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Tracking Algorithm

The initial state of the tracking algorithm

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Tracking Algorithm

Predict the position of every drop based on existing data

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Tracking Algorithm

Add the matching centroids, try to acquire new drops

Fractional Charge Search

Tracking Algorithm

The algorithm has completed a full cycle.

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E Field Calibration

Stokes’s Law can be written:

Since

is quantized, the value of

can be calibrated directly from the data by plotting

vs.

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Airflow Measurement

The measured airflow profile is parabolic. Fluctuations in the horizontal direction have an RMS of

Fractional Charge Search

Centroiding and Brownian Motion

b c a x,c

∆

x,b

∆

• ❻❼

• ❽

• ◗

• ❽

• ❾

• ❽

• ◗

• ❻❼

• ❾

• ◗

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Radius Measurement

• quantization in

• ✣

measurement

• Brownian motion amplitude
• direct optical measurement
• time constant to terminal velocity
• induced dipole effects
• deceleration from evaporation

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Complications

θ 1 R 2 vx

Fluid dynamic coupling of the drops through the air is the rate limiting factor

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Selection Criteria

A total of

• f the drops were removed

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Results

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Results

drops,

silicone oil less than

FCPs per nucleon see hep-ex/0204003

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Future Plans

• Find

techniques for handling larger drops

• Continue

to improve meteorite suspension

• Develop new analysis tools
• Conduct the meteorite experiment

Fractional Charge Search

Additional Analysis Components

• Calibration of E Field value
• Correction for E Field non-uniformity
• Calibration of airflow value
• Correction for airflow non-uniformity
• Optical size measurement of drops
• Optical y-axis position measurement
• Brownian motion and Centroiding error
• Correction for drop to drop interaction
• Development of cuts for final analysis