Andrew W Alexander

US Patent:

20210407782, Dec 30, 2021

Filed:

Sep 8, 2021

Appl. No.:

17/468841

Inventors:

- Bloomington IN, US
Andrew W. Alexander - Bloomington IN, US
Aaron R. Todd - Bloomington IN, US

International Classification:

H01J 49/02
H01J 49/00
H01J 49/42

Abstract:

A CDMS may include an ELIT having a charge detection cylinder (CD), a charge generator for generating a high frequency charge (HFC), a charge sensitive preamplifier (CP) having an input coupled to the CD and an output configured to produce a charge detection signal (CHD) in response to a charge induced on the CD, and a processor configured to (a) control the charge generator to induce an HFC on the CD, (b) control operation of the ELIT to cause a trapped ion to oscillate back and forth through the CD each time inducing a charge thereon, and (c) process CHD to (i) determine a gain factor as a function of the HFC induced on the CD, and (ii) modify a magnitude of the portion of CHD resulting from the charge induced on the CD by the trapped ion passing therethrough as a function of the gain factor.

US Patent:

20190164739, May 30, 2019

Filed:

Jan 31, 2019

Appl. No.:

16/264023

Inventors:

- Bloomington IN, US
Deven L. Shinholt - Pflugerville TX, US
Staci N. Anthony - Bloomington IN, US
Andrew W. Alexander - Bloomington IN, US

International Classification:

H01J 49/42
H01J 49/00

Abstract:

A quadrupole mass filter and method for operating the filter are described. Sample ions, each having a mass-to-charge ratio, are passed to a quadrupole at least one AC voltage is applied thereto to separate the ions by incrementally varying a frequency of the at least one AC voltage within a first range of frequencies and, for each of at least some of the incremental frequencies in the first range of frequencies, incrementally varying an amplitude of the at least one AC voltage within a range of amplitudes, wherein each incremental frequency and incremental amplitude pair of the at least one AC voltage creates a different band pass filter in the quadrupole through which produced ions having a different corresponding mass-to-charge ratio pass to a detector.

US Patent:

20180277350, Sep 27, 2018

Filed:

Nov 6, 2015

Appl. No.:

15/524354

Inventors:

- Indianapolis IN, US
Deven L. SHINHOLT - Pflugerville TX, US
Staci N. ANTHONY - Bloomington IN, US
Andrew W. ALEXANDER - Bloomington IN, US

International Classification:

H01J 49/42
H01J 49/00

Abstract:

A quadrupole mass filter and method for operating the filter are described. AC voltages are applied to the quadrupole to separate ions based on mass-to-charge ratio. Frequency is scanned with a simultaneous amplitude scan. Ions are measured over a broad m/z range with high resolution. A resolving power of about 1,200 was demonstrated. Ions were observed for m/z values over 150,000 Th.