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
� � ✁ Research Interests Fractional Charge Search 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
� � � � � � Outline Fractional Charge Search Motivation Millikan’s Technique Apparatus Software Analysis Future Plans
� � Background Fractional Charge Search Search Techniques – Accelerator – Cosmic rays – Levitometer – Millikan Implications of null result – Extremely rare – May have high mass – Unpredictable distribution
� � � FCP Candidates Fractional Charge Search 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 observation. Dark Matter Recent papers have shown that it is possible for dark matter to be composed of fundamental charged particles (CHAMPS).
✝ ✆ ✝✠ Bulk Matter Searches Fractional Charge Search 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
� � � � � Millikan’s Method Fractional Charge Search 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
✣ ✛✜ ✗ ✮ ★ ✧ ✮ ✔ ✫ ✢ ✮ ✛✜ ✗ ★✭ ✓ ✮ ✎✏ ✔ ☛ ✡ Experimental Principle Fractional Charge Search x Airflow Duct z ✡✒✑ ☞✍✌ Falling Drop Electric ✔✖✕ ✔✖✣✥✤ ✘✚✙ ✣✥✦ Field Plate ✔✪✩ ✔✖✣✬✫ ✘✚✙ High Voltage ✔✖✣✥✤ Laminar Air Flow
❉ ❀ ✵ ✶ ✯ ✰ ✼ ✱ ✿ ✵ ✶ ✵ ✾ ✫ ✯ ✾ ✱ ❄ ★ ❅ ❆ ❇ ❆❈ ✿ ✼ ✰ ✯ ✲ ✓ ✣ ✫ ✯ ✳ ✴✵ ✶ ✺ ✻ ✯ ✜ ✘ ✴ ✵ ✶ ✣ ✤ ✯ ✰✱ Operating Point ✣✥✦ ✦❁❃❂ ✷✹✸ Fractional Charge Search ✰✽✼
� � � � � � Throughput Limitations Fractional Charge Search 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
Apparatus Fractional Charge Search Strobed LED Array Microdrop Ejector Airflow Duct Transparent Walls Camera CCD Electric Field Plate Lens X Y Transparent Outer Chamber Z Entrance Tube for Air
Apparatus Fractional Charge Search
Drop on Demand Fluid Ejector Fractional Charge Search
❦ ❧ ❣❤✐ ❡ ❢ ❩ ❱ ❣❤✐ ❥ ❋ ❞ P ❑ ♠ ❑ ❣❤ ✐ ❋ ❞ ❦ ♥ P ❝ ❭ ❥ ◗ ❑ ♠ ❊ P ❏ ♦ ❦ ❖ P P ❴ ❘ ❙❚ ❯ ❱ ❞ ❩❬ ❋ ❙ ❪ ♠ Airflow Tube Fractional Charge Search The airflow profile across the chamber cross section is determined by the solution to Poisson’s equation. ❲❨❳ P☎❞ ❵❜❛ ❋❍●❃■ ❑❃▲ ▼✒◆ ❭❫❪ 1 0.8 0.83 cm 0.6 0.4 0.2 -3 -2 -1 1 2 3 3.12 cm
Airflow System Fractional Charge Search
E Field Plates Fractional Charge Search
Apparatus Fractional Charge Search Strobed LED Array Microdrop Ejector Airflow Duct Transparent Walls Camera CCD Electric Field Plate Lens X Y Transparent Outer Chamber Z Entrance Tube for Air
Electronics Fractional Charge Search Image Data Sparse Data CCD Camera Computer Field Index Frequency Divider Data Storage 10 Hz Clock HV Power Supply Pulse Generator +V −V HV Pulse Amplifier HV Monitor LED Driver High Voltage Switcher LED Light Source Electric Field Plates Drop Generator LED Pulses E Field 1 s 1 s
� � � � Software Tasks Fractional Charge Search Data acquisition Image processing Pattern recognition Analysis and diagnostics
� � Computing Fractional Charge Search 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
✵ ✫ q r ▲ ❁ ✉ ● t ❂ q ✁ ♣ Image Processing Fractional Charge Search qr✥s q✥✈
� � � � � Tracking Algorithm Fractional Charge Search 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.
Tracking Algorithm Fractional Charge Search The problem to be solved
Tracking Algorithm Fractional Charge Search The initial state of the tracking algorithm
Tracking Algorithm Fractional Charge Search Predict the position of every drop based on existing data
Tracking Algorithm Fractional Charge Search Add the matching centroids, try to acquire new drops
Tracking Algorithm Fractional Charge Search The algorithm has completed a full cycle.
⑨ ⑤ ❸ ❷ ❶ ⑩ ⑨ ★ ⑧ ⑤ ④ ✇ ✣ ✫ ✗ ✫ E Field Calibration Fractional Charge Search ✇⑦⑥ Stokes’s Law can be written: ①③② Since is quantized, the value of can be calibrated directly from the data by plotting vs. ❹❻❺
▼ ✁ q q ✈ ✵ ❂ Airflow Measurement Fractional Charge Search The measured airflow profile is parabolic. Fluctuations in the horizontal direction have an RMS of
❾ ❚ ◗ ❪ ➁ ❚ ➀ ➅ ❭ ❪ ◆ ❚ ❪ ❘ ❪ ▲ ◗ ♣ ▲ ◗ ● ◆ ❾ ● ➃ ❾ ❪ ❽ ❪ ➆ ➅ ❪ ➅ ❚ ♣ ◆ ▲ ➆ ❾ ❪ ➁ ➀ ◗ ❪ ➁ ➀ ❾ ➀ ❚ ♣ ➇ ❘ ◗ ❚ ♣ ▲ ➆ ❾ ❪ ➁ ❚ ◆ ❭ ❘ ◗ ♣ ❘ ● ▲ ❾ ● ❭ ❪ ❘ ❭ ❪ ♣ ❪ ❘ ❽ ● ▲ ◗ ● ❽ ❪ ❘ ❽ ● ▲ ◗ ❽ ❭ ❪ ❭ ❪ ◗ ♣ ▲ ❘ ◗ ● ➃ ◗ ◆ ❚ ❪ ❘ ❚ ❪ ◗ ♣ Centroiding and Brownian Motion ♣❿❾ ♣❿❾ ♣❿❾ ♣❿❾ ♣❿❾ ♣❿❾ ♣❿❾ ●❻❼ ●❻❼ ➀➂➁ ➀➄➁ b x,c x,b ∆ ∆ c a Fractional Charge Search
� � � � ✣ ✫ � ✣ ✤ � � Radius Measurement Fractional Charge Search quantization in measurement Brownian motion amplitude direct optical measurement time constant to terminal velocity induced dipole effects deceleration from evaporation
Complications Fractional Charge Search Fluid dynamic coupling of the drops through the air is 1 v x θ the rate limiting factor R 2
✓ ✰ ✰ ✾ ➓ ✓ ✓ ➔ ➐ ➑ → ➒ ✮ ➈ ✱ ✼ ➉ ✱ ⑧ ✓ ✾ ✘ ✼ ✱ ➍ ↔ ✓ ✤ t ✫ ✈ ➣ ✓ ✼ ➈ ✮ ➋ ✯ ✰ ✰ ★ ➈ ➉ ✼ ➊ ✸ ✺ ⑨ ➈ ✱ ✼ ✱ ✸ r ➒ ➑ ➐ ✤ ✣ ➌ ✮ ◆ ✰✱ ➍ ➇ of the drops were removed Selection Criteria ✰➏➎ ✻➙↕ ✣✥✤ ✮✹→ A total of Fractional Charge Search
Results Fractional Charge Search
✕ ➎ ✰ ✰✱ ◆ ➇ ✓ ✱ ✳ ✯ ➇ ① ✰✱ ➎ ✳ ✰ ✳ Results Fractional Charge Search drops, silicone oil less than FCPs per nucleon ✰✽✼ see hep-ex/0204003
� � � � Future Plans Fractional Charge Search Find techniques for handling larger drops Continue to improve meteorite suspension Develop new analysis tools Conduct the meteorite experiment
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