Physics Research | John Boyd's Website

SUMMARY OF RESEARCH

I am currently finishing up my PhD at the University of Virginia (May 2024). My field of specialty is Experimental Particle & Nuclear Physics with a focus on gas electron multiplier (GEM) detector R&D, analysis/characterization, and maintenance/sustainability.

My research focuses on the design, production, installation, testing, and operation of gas electron multiplier (GEM) detectors. In particular, those for the Jefferson Lab Super BibBite Spectrometer (SBS) project. I have collaborated in the design of a novel GEM detector and will lead efforts for installing and commissioning a series of these new devices at Jefferson Lab in Newport News, VA. The SBS project, equipped with these ground-breaking detectors, will usher in a new generation of high-precision experiments (GEp-V, GEn-II, GEn-RP, and GMn, to name a few) in order to measure the electromagnetic form factor (EMFF) of the nucleon at increased momentum transfers.

RESEARCH REALIZED

The newly designed and developed UV GEM detectors incorporate many new and unique features which greatly enhance experimental and analytical capabilities. They are the largest active area GEM detectors to be built as-to-date (40 cm x 150 cm). They are built on the platform of a readout plane utilizing a UV coordinate basis (a "rotated" XY schema). This, in conjunction with additional layers of XY detectors, allows for increased particle speeds and number of particles while also reducing the overlapping coincidence combinatories for analyzing particle tracks over several GEM layers.

In addition to the physical component and integrated assembly design, I have also developed several apparatus for assembling, testing, and peformance characterization of GEM detectors.

To view technical figures & information click here.

PHYSICS BASICS

GEMs (gas electron multipliers) are a type of gaseous ionization particle detector. They are gas filled chambers made up of multiple layers of high-voltage electrodes (or "foils"). They are primarily used for path tracking and position coordination in particle physics experiments at laboratories such as Jefferson Lab, CERN, Fermilab, etc. GEMs are well-suited for high-energy and nuclear physics experiments because they can handle environments with high energies and rates of particles.

GEMs as particle trackers at JLab.

A GEM electrode consists of two metal-coated sides separated from each other by a central (kapton) polymer. Each foil is densely populated with a matrix of "perforations" and the two metal coatings are held at a potential different on the order of ~400 V.

Detailed views of a GEM foil's perforations and their field lines.

Schematic of GEM eletrode foil and field lines.

After the accelerator beam encounters a "target", it produces particles downstream of it. These production particles will then encounter the tracking detectors. These particles are able to pass through the grid of holes in the layers of GEM foils. Due to the large electric field in the region of the perforations, an avalanche of electrons is created through ionization collisions in those gap regions.

Working principle of a GEM detector:

A charged particle is incident on the detector.
The particle radiates as it decelerates upon incidence.
This radiation causes ionization in the chamber's gas.
Electrons and ions drift apart in the electric field between each of the layers.
An "avalanche" process is developed in the regions of strong electrostatic field (at each layer or the GEM).
Through the avalanche(s), new electron-ion pairs are created.
These new particles also ionize and the process repeats.
This series of avalanches is able to produce enough electrons at the final detector layer to create a charge large enough to be detected by electronics.
Thus, the final layer of the detector is a Readout plane which maps the 2D position of the incident particle.
GEMs can be stacked or layered with other GEMs and a 3D path can be constructed from the combined 2D information.

A particle ionizes, avalanches, and lands on the Readout Plane.

The beauty of GEM detectors is that they take a single incident charged particle (which is so small it is hard to accurately determine its location/position) and "multiply" into a sizeable amount of particles which can be measured and tracked for their positions.

SUMMARY OF RESEARCH

RESEARCH REALIZED

In addition to the physical component and integrated assembly design, I have also developed several apparatus for assembling, testing, and peformance characterization of GEM detectors.

To view technical figures & information click here.

PHYSICS BASICS

GEMs as particle trackers at JLab.

A GEM electrode consists of two metal-coated sides separated from each other by a central (kapton) polymer. Each foil is densely populated with a matrix of "perforations" and the two metal coatings are held at a potential different on the order of ~400 V.

Detailed views of a GEM foil's perforations and their field lines.

Schematic of GEM eletrode foil and field lines.

Working principle of a GEM detector:

A charged particle is incident on the detector.

The particle radiates as it decelerates upon incidence.

This radiation causes ionization in the chamber's gas.

Electrons and ions drift apart in the electric field between each of the layers.

An "avalanche" process is developed in the regions of strong electrostatic field (at each layer or the GEM).

Through the avalanche(s), new electron-ion pairs are created.

These new particles also ionize and the process repeats.

This series of avalanches is able to produce enough electrons at the final detector layer to create a charge large enough to be detected by electronics.

Thus, the final layer of the detector is a Readout plane which maps the 2D position of the incident particle.

GEMs can be stacked or layered with other GEMs and a 3D path can be constructed from the combined 2D information.

A particle ionizes, avalanches, and lands on the Readout Plane.

The beauty of GEM detectors is that they take a single incident charged particle (which is so small it is hard to accurately determine its location/position) and "multiply" into a sizeable amount of particles which can be measured and tracked for their positions.

Configuration of Readout wires/strips.

Particle track, amplifying avalanche, and signal on Readout.

SUMMARY OF RESEARCH

RESEARCH REALIZED

In addition to the physical component and integrated assembly design, I have also developed several apparatus for assembling, testing, and peformance characterization of GEM detectors.

​

To view technical figures & information click here.

PHYSICS BASICS

GEMs as particle trackers at JLab.

A GEM electrode consists of two metal-coated sides separated from each other by a central (kapton) polymer. Each foil is densely populated with a matrix of "perforations" and the two metal coatings are held at a potential different on the order of ~400 V.

Detailed views of a GEM foil's perforations and their field lines.

Schematic of GEM eletrode foil and field lines.

Working principle of a GEM detector:

A charged particle is incident on the detector.

The particle radiates as it decelerates upon incidence.

This radiation causes ionization in the chamber's gas.

Electrons and ions drift apart in the electric field between each of the layers.

An "avalanche" process is developed in the regions of strong electrostatic field (at each layer or the GEM).

Through the avalanche(s), new electron-ion pairs are created.

These new particles also ionize and the process repeats.

This series of avalanches is able to produce enough electrons at the final detector layer to create a charge large enough to be detected by electronics.

Thus, the final layer of the detector is a Readout plane which maps the 2D position of the incident particle.

GEMs can be stacked or layered with other GEMs and a 3D path can be constructed from the combined 2D information.

A particle ionizes, avalanches, and lands on the Readout Plane.

The beauty of GEM detectors is that they take a single incident charged particle (which is so small it is hard to accurately determine its location/position) and "multiply" into a sizeable amount of particles which can be measured and tracked for their positions.

Configuration of Readout wires/strips.

Particle track, amplifying avalanche, and signal on Readout.