Patents by Inventor Philip A. Freedman

Philip A. Freedman has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5471059
    Abstract: A multiple charged-particle detector system includes a plurality of charged-particle detector assemblies (10-12) which are each made up of a first arm (19-22) and a second arm (24-27) extending at an angle to each other. Charged particles (4-7) enter an aperture (14-18) at the entrance of the first arm (19-22) of each detector assembly (10-12) and strike a dynode (30-33) positioned at the intersection of the two arms causing electrons to be emitted by the dynode (30-33). Some of the electrons pass into the second arms (24-27) of the detector assemblies (10-12) and are detected by a continuous-dynode electron multiplier (35-38). The first arms (19-22) are narrower than the detectors (35-38), and the detector assemblies (10-12) are arranged in such a way that the minimum separation at which charged-particle beams (4-7) can be detected is determined by the widths of the said first arms (19-22) of the detector assemblies (10-12), and not by the widths of the detectors (35-38) themselves.
    Type: Grant
    Filed: December 16, 1994
    Date of Patent: November 28, 1995
    Assignee: Fisons PLC
    Inventors: Philip A. Freedman, Edward F. H. Hall
  • Patent number: 5352893
    Abstract: An isotopic-ratio mass spectrometer comprises an r.f.
    Type: Grant
    Filed: July 22, 1993
    Date of Patent: October 4, 1994
    Assignee: Fisons plc
    Inventor: Philip A. Freedman
  • Patent number: 5166518
    Abstract: A mass spectrometer comprising ion source means (1) for producing ions characteristic of a sample to be analysed; ion detector means (14) for receiving at least some of said ions; magnetic sector analyzing means (18) and electrostatic analyzing means (8) disposed in any order between said ion source means (1) and said ion detector means (14); wherein said magnetic sector analyzing means (18) comprises means for dispersing ions according to their mass-to-charge ratios and for transmitting ions whose mass-to-charge ratios lie within a predetermined range and have a first kinetic energy; said electrostatic analyzing means (8) comprises means for generating an electrostatic field for deflecting ions having different kinetic energies around different curved trajectories such that ions having a second kinetic energy, lower than said first kinetic energy, are deflected around a central curved trajectory (15) and transmitted through said electrostatic analyzing means (8), and the strength of said electrostatic field
    Type: Grant
    Filed: December 9, 1991
    Date of Patent: November 24, 1992
    Assignee: Fisons Plc
    Inventor: Philip A. Freedman
  • Patent number: 4916313
    Abstract: The invention provides a method and apparatus for the mass spectrometric determination of the isotopic composition of an element comprised in a sample by gas chromatography-isotopic ratio mass spectrometry. As a sample elutes from the column of the gas chromatograph it enters a sample conversion means which converts the element to an analysis gas (a gas comprising the element in elemental form or in the form of a simple compound, e.g. nitrogen or carbon dioxide) which is admitted into the mass spectrometer only during a second time interval corresponding to the elution of the peak containing the sample from the column. One or more calibration samples of a reference gas are admitted into the spectrometer during first time intervals which do not overlap the second time interval, thereby minimizing the contribution of the analysis gas to the reference gas mass analysis, and vice versa. Various devices are provided to minimize disturbance to the flow of gas into the spectrometer during practice of the method.
    Type: Grant
    Filed: August 31, 1988
    Date of Patent: April 10, 1990
    Assignee: VG Instruments Group Limited
    Inventors: Keith Hall, Philip A. Freedman, Elizabeth J. Jumeau, Roger Guilluy, Christiane Pachiaudi, Jean P. Riou
  • Patent number: 4866270
    Abstract: The invention comprises methods and apparatus for the mass spectrometric determination of the isotopic composition of an element comprised in an analysis gas (that is, a gas comprising the element in elemental form or in the form of a simple compound, e.g., nitrogen or carbon dioxide). First and second flows of a carrier gas (e.g., helium) are simultaneously passed into the mass spectrometer, and samples of analysis gas and a reference gas are respectively introduced into the first and second flows during selected time intervals. The time intervals are selected so that mass spectrometric measurements are made on the analysis gas samples in the absence of any signal from the reference gas samples, and v.v. A preferred embodiment comprises a gas chroatograph through which a sample containing the element is passed, and conversion means to convert the eluting sample into the analysis gas.
    Type: Grant
    Filed: August 31, 1988
    Date of Patent: September 12, 1989
    Assignee: VG Instruments Group Limited
    Inventors: Keith Hall, Philip A. Freedman, Elizabeth J. Jumeau, Roger Guilluy, Christiane Pachiaudi