Developing a Low Noise Seismometer in the Frequency Range of 0.3Hz - - PowerPoint PPT Presentation

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Developing a Low Noise Seismometer in the Frequency Range of 0.3Hz - - PowerPoint PPT Presentation

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Developing a Low Noise Seismometer in the Frequency Range of 0.3Hz to 20 Hz Gregory E. Vansuch University of Colorado at Boulder August 19, 2010 Mentors: Dr. Jan Harms, California Institute of Technology Dr. Riccardo DeSalvo, California

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Developing a Low Noise Seismometer in the Frequency Range of 0.3Hz to 20 Hz

Gregory E. Vansuch University of Colorado at Boulder August 19, 2010

Mentors:

  • Dr. Jan Harms, California Institute of Technology
  • Dr. Riccardo DeSalvo, California Institute of Technology

LIGO-G1001115-v1

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LIGO SURF 2010

Overview

  • Introduction
  • Limitations of Seismometers
  • Improved Noise Models
  • AutoCAD Design Analysis
  • The Next Stage

2 Gregory E. Vansuch

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Introduction

Why?

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Graph of Noise in Future Detectors

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LIGO SURF 2010

“Seismically Induced” Newtonian Noise

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Seismic fields create perturbations in the ground causes the ground to displace ever so slightly this changes the density around a test mass induces a force upon the mass which displaces it ever so slightly. This is Newtonian Noise

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Simple Look and Possible Solution

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Learn about Newtonian Noise at Homestake

  • Develop methods to subtract it

2-D Model of NN:

∆y

∆x

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Homestake

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Limitations of Seismometers

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Capacitor Readout vs. Coil Readout

  • Coil Readout
  • too high sensor

impedance = more noise

  • A capacitor has as little resistance as
  • ne can make it with

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Sensitivity

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Frequency [Hz] Seismic [(m/s)/ Hz] GS-13 / LT1012 Amplifier voltage noise Amplifier current noise Johnson–Nyquist noise Suspension thermal noise Total Noise

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Improved Noise Models

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Mathematics with the Capacitor Addition

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Transfer Function

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Graphs from Transfer Function

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Frequency [Hz] Seismic [(m/s)/ Hz] GS-13 / LT1012 Amplifier voltage noise Amplifier current noise Johnson–Nyquist noise Suspension thermal noise Total Noise

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Frequency [Hz] Seismic [(m/s)/ Hz] ET-C LIGO 2.5 GS-13 / LT1012

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AutoCAD Design and Analysis

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Dimensions to 3-D Models

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Cross Section

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  • Possibly no room

for capacitor at bottom due to the calibration coil taking up too much space.

Calibration coil

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SLIDE 20

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Add on to the outside cylinder to make room? Capacitor plate here Capacitor plate here

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PCB

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What is Next?

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Short Term

  • Complete the setup of newly arrived

seismometers

  • Noise measurements with the

seismometers

  • Find out the major limitations and

determine how to lower these limits

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Long Term

  • In the next year get into Homestake and

begin more seismic measurements for modeling NN

  • Over the next few years keep modifying

seismometers for less limitations and better seismic study

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SLIDE 25

Acknowledgements

Jan Harms Riccardo DeSalvo Aiden Brooks Alastair Heptonstall The 40m team for letting us steal their instrument The rest of the LIGO Community

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Refrences

  • Brooks, Aiden. notes from personal conversations. June 2010.
  • Hans, Jan. notes from personal conversations. June 9-August 18, 2010.
  • Harms, Jan, et al. Characterization of the seismic environment at the Sanford

Underground Laboratory, South Dakota. LIGO Document, DRAFT, 2010.

  • Harms, Jan, Vansuch, Greg. Seismometers and the Insulation Box. LIGO

document, M1000204v-1, 2010.

  • Harms, Jan; Vansuch, Greg. Subtraction of Newtonian Noise. LIGO document,

M1000203-v1, 2010.

  • Harms, J., Sajeva, A., Trancynger, T., DeSalvo, R., Mandic, V. Seismic studies

at the Homestake mine in Lead, South Dakota. LIGO document, page T0900112-v1-H, 2010.

  • Heptonstall, Alastair. personal conversation. July 26, 2010.
  • Jones, R.V. and Richards, J.S.C. The Design and some applications of sensitive

capacitance micrometers.J. Phys. E: SciInstrum, 1973.

  • Mandic, Vuk. Status of the Seismic Noise Study at the Homestake Mine

(DUSEL).LIGO document, page G080491-00-Z, 2008.

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