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LIGO Basic Training Begins

LIGO Basic Training Begins

- Contributed by Fred Raab

Building and operating a gravitational-wave detector requires a broad spectrum of skills, and the resident staff at LIGO Hanford Observatory is a pretty diverse group of people. Some are Ph.D. physicists who have expertise from various experiments. Some are senior engineers, who have designed, built or worked on major high-tech facilities like a particle accelerator or radio astronomy observatory. Some got their high-tech background working on projects with the U.S. Navy, either in service or as a contractor. Some are recent college graduates. Areas of staff expertise include physics, geophysics, civil engineering, electrical and electronics engineering, mechanical engineering, software engineering and vacuum engineering. Because of the newness of this field, very few people have experience with precision laser interferometers. And absolutely no one has experience with kilometer sized interferometers, because LIGO's 2-km interferometer at Hanford will be the first of its kind!

Figure 1. Ever since work began toward using laser interferometers to detect gravitational waves in the early 1970's, the U.S. effort has been centered around test interferometers operated by small groups of Ph.D. physicists and graduate students at Caltech and MIT. Over the past decade, there have been typically only about a dozen people in the U.S. who could be "left alone" to operate one of these gravitational-wave detector test beds. The challenge now is to come up with about two dozen people at both of the Hanford and Livingston observatories, who can run, diagnose and fix interferometers and manage the online data analysis.

How do you quadruple the knowledgeable population of interferometer experts in a few short years? One aspect of a solution has been to design and build equipment with more of a "turn-key" nature than the campus test beds, which were designed to be operated by the designers. The second is to find people with a range of skills and backgrounds, lots of enthusiasm, a sense of adventure, and then fill in whatever else is needed to make them experts in this new field. At Hanford we have been able to attract people with the requisite qualities early, and to have them work with the designers to install and commission hardware. Now that people have developed a visual memory of the hardware, and knowledge of the practical aspects of the instrumentation, the time is ripe for a systematic education in interferometer science and engineering.

The first step in that education is LIGO Basic Training, a series of lectures aimed at developing a common set of conceptual tools for understanding the science of LIGO. Topics will include Basic Calculus, Spectral Analysis, Statistics, Basic Electronics, Vacuum Practice, Mechanics, Geophysics, Thermodynamics, Optics, Quantum Mechanics, Special Relativity, General Relativity and Astronomy. The emphasis of LIGO Basic Training is on concepts rather than details. For instance, visualizing a partial derivative counts for more than being adept at calculating it, since a computer would likely do the calculation in daily operations if needed. A second course of lectures, to be entitled The Physics of LIGO, will follow up later with a much deeper treatment Figure 2. of interferometer issues. This course will be derived from a course of similar name organized a few years ago at Caltech by Professor Kip Thorne, in which LIGO scientists and graduate students presented lectures to their faculty and student colleagues.

So far LIGO Basic Training has had four of the weekly lectures, presented by Fred Raab, covering calculus, Fourier transforms, transfer functions, power spectrum estimation and probability distributions. In Figure 1 at left above, Fred is trying to help people visualize vector fields that have non zero curl or divergence. And in Figure 2 at right, vacuum engineer Kyle Ryan asks a question to try to nail down this picture. Sometimes it helps to go outside the lecture format to pin down understanding of a new concept. Scientist Rick Savage recently demonstrated a number of aspects of working in frequency space, using a signal analyzer to measure thermal noise from a resistor and to identify the presence of a coherent signal added to this noise. Pretty soon the first projects will be assigned to make a "hands-on" connection to the concepts developed in class.