US5023449A — Nuclear spectroscopy signal stabilization and cal…

Claim 1

Independent Claim 122 words

Nuclear spectroscopy method for the stabilization of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by said radiation detector, said energy spectrum including at least a first reference energy peak coming from an ancillary nuclear source, comprising the steps of: (1) using at least two detectors for detecting the radiation under analysis; (2) establishing at least one coincident spectrum corresponding to pairs of events simultaneously detected in both detectors and coming from said ancillary source; and (3) stabilizing said coincident spectrum by using one energy peak of said spectrum as said first reference energy peak.

Claim 2

Dependent Claim 122 words

Nuclear spectroscopy method for the stabilization of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by said radiation detector, said energy spectrum including at least a first reference energy peak coming from an ancillary nuclear source, comprising the steps of: (1) using at least two detectors for detecting the radiation under analysis; (2) establishing at least one coincident spectrum corresponding to pairs of events simultaneously detected in both detectors and coming from said ancillary source; and (3) stabilizing said coincident spectrum by using one energy peak of said spectrum as said first reference energy peak.

Claim 3

Dependent Claim 22 words

The method according to claim 1 wherein said ancillary nuclear source is placed between the respective facing ends of said two detectors.

Claim 4

Dependent Claim 16 words

The method according to claim 1 wherein said detectors are both made of bismuth germanate crystal.

Claim 5

Dependent Claim 31 words

The method according to claim 1 wherein the nuclear activity of said ancillary source corresponds to a level which is substantially smaller than the activity level of the radiation under analysis.

Claim 6

Dependent Claim 22 words

The method according to claim 1 further including the step of establishing a non coincident spectrum representative of the non coincident events.

Claim 7

Dependent Claim 15 words

The method according to claim 1 wherein the ancillary source is made of 22 Na.

Claim 8

Dependent Claim 33 words

The method according to claim 1 wherein a spectrum calibrating step (for offset correction) of the coincident spectrum is carried out by using said first reference peak and a second reference energy peak.

Claim 9

Dependent Claim 17 words

The method according to claim 7 wherein said second reference energy peak comes from said ancillary source.

Claim 10

Dependent Claim 24 words

The method according to claim 7 wherein said first reference peak is at 0.511 MeV, and said second reference peak is at 1.78 MeV.

Claim 11

Dependent Claim 41 words

The method according to claim 7 wherein said calibrating step further uses a third reference energy peak, and wherein said second energy peak has an energy value which is the sum of the energy values of said first and third peaks.

Claim 12

Dependent Claim 22 words

The method according to claim 6 wherein said ancillary source is surrounded by a layer of material having a high atomic number.

Claim 13

Dependent Claim 23 words

The method according to claim 1 further establishing a coincident spectrum for each of the detectors, and stabilizing each of said coincident spectra.

Claim 14

Dependent Claim 35 words

The method according to claim 7 wherein said stabilizing step and said calibrating step are carried out periodically, and wherein the period of the stabilizing step is shorter than the period of the calibrating step.

Claim 15

Dependent Claim 124 words

Nuclear spectroscopy apparatus for the stabilization of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by said radiation detector, said energy spectrum including at least a first reference energy peak coming from an ancillary nuclear source, comprising: (1) at least two detectors for detecting the radiation under analysis; (2) means for establishing at least one coincident spectrum corresponding to a pair of events simultaneously detected in both detectors and coming from said ancillary source; and (3) means for stabilizing said coincident spectrum by using one energy peak of said coincident spectrum as said first reference energy peak.

Claim 16

Dependent Claim 124 words

Nuclear spectroscopy apparatus for the stabilization of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by said radiation detector, said energy spectrum including at least a first reference energy peak coming from an ancillary nuclear source, comprising: (1) at least two detectors for detecting the radiation under analysis; (2) means for establishing at least one coincident spectrum corresponding to a pair of events simultaneously detected in both detectors and coming from said ancillary source; and (3) means for stabilizing said coincident spectrum by using one energy peak of said coincident spectrum as said first reference energy peak.

Claim 17

Dependent Claim 22 words

The apparatus according to claim 14 wherein said ancillary nuclear source is placed between the respective facing ends of said two detectors.

Claim 18

Dependent Claim 19 words

The apparatus according to claim 14 wherein at least one of said detectors is made of bismuth germanate crystal.

Claim 19

Dependent Claim 25 words

The apparatus according to claim 14 further comprising means for establishing, for each detector, a coincident spectrum and further means for stabilizing both coincident spectra.

Claim 20

Dependent Claim 69 words

The apparatus according to claim 14 wherein said means for establishing coincident spectrum includes a set of two memories for each detector, to wit a first memory for coincident spectrum and a second memory for non coincident spectrum, and a coincident circuit connected to the output of both detectors and able to, upon coincidence or non coincidence determination, direct data from the respective detectors, to the suitable corresponding memory.

Claim 21

Dependent Claim 36 words

The apparatus according to claim 14 wherein the ancillary source is made of 22 Na, allowing the simultaneous emission of a pair of opposed directions gamma rays of 0.511 Mev, and a 1.27 Mev gamma ray.

Claim 22

Dependent Claim 30 words

The apparatus according to claim 14 further including means for calibrating said coincident spectrum (for offset correction) designed to use said first reference peak and a second reference energy peak.

Claim 23

Dependent Claim 17 words

The apparatus according to claim 20 wherein said second reference energy peak comes from said ancillary source.

Claim 24

Dependent Claim 24 words

The apparatus according to claim 20 wherein said first reference peak is at 0.511 MeV, and said second reference peak is at 1.78 MeV.

Claim 25

Dependent Claim 41 words

The apparatus according to claim 20 wherein said calibrating means further uses a third reference energy peak, and wherein said second energy peak has an energy value which is the sum of the energy values of said first and third peaks.

Claim 26

Dependent Claim 23 words

The apparatus according to claim 14 wherein said ancillary source is surrounded by a layer of material having a high atomic number Z.

Claim 27

Dependent Claim 144 words

A logging nuclear spectroscopy method for the stabilization of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by said radiation detector, and coming from earth formations surrounding a borehole in which is lowered a logging tool including said detector, said energy spectrum including at least a first reference energy peak coming from an ancillary nuclear source, said method comprising the steps of: (1) using at least two detectors for detecting the radiation under analysis; (2) establishing at least one coincident spectrum corresponding to pairs of events simultaneously detected in both detectors and coming from said ancillary source; and (3) stabilizing said coincident spectrum by using one energy peak of said spectrum as said first reference energy peak.

Claim 28

Dependent Claim 144 words

A logging nuclear spectroscopy method for the stabilization of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by said radiation detector, and coming from earth formations surrounding a borehole in which is lowered a logging tool including said detector, said energy spectrum including at least a first reference energy peak coming from an ancillary nuclear source, said method comprising the steps of: (1) using at least two detectors for detecting the radiation under analysis; (2) establishing at least one coincident spectrum corresponding to pairs of events simultaneously detected in both detectors and coming from said ancillary source; and (3) stabilizing said coincident spectrum by using one energy peak of said spectrum as said first reference energy peak.

Claim 29

Dependent Claim 38 words

The method according to claim 25 wherein a spectrum calibrating step (for offset correction) of the coincident spectrum is carried out by using said first reference peak and a second reference energy peak coming from said ancillary source.

Claim 30

Dependent Claim 141 words

A logging nuclear spectroscopy apparatus for the stabilization of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by said radiation detector, and coming from earth formations surrounding a borehole in which is lowered a logging tool including said detector, said energy spectrum including at least a first reference energy peak coming from an ancillary nuclear source, comprising: (1) two detectors for detecting the radiation under analysis; (2) means for establishing at least one coincident spectrum corresponding to pairs of events simultaneously detected in both detectors and coming from said ancillary source; and (3) means for stabilizing said coincident spectrum by using one energy peak of said coincident spectrum as said first reference energy peak.

Claim 31

Dependent Claim 141 words

A logging nuclear spectroscopy apparatus for the stabilization of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by said radiation detector, and coming from earth formations surrounding a borehole in which is lowered a logging tool including said detector, said energy spectrum including at least a first reference energy peak coming from an ancillary nuclear source, comprising: (1) two detectors for detecting the radiation under analysis; (2) means for establishing at least one coincident spectrum corresponding to pairs of events simultaneously detected in both detectors and coming from said ancillary source; and (3) means for stabilizing said coincident spectrum by using one energy peak of said coincident spectrum as said first reference energy peak.

Claim 32

Dependent Claim 38 words

The apparatus according to claim 27 wherein it further includes means for calibrating said coincident spectrum (for offset correction) designed to use said first reference peak and a second reference energy peak which comes from said ancillary source.

Claim 33

Dependent Claim 133 words

Nuclear spectroscopy method for the offset correction of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by said radiation detector, said energy spectrum including at least a first reference energy peak coming from an ancillary nuclear source, comprising the steps of: (1) using at least two detectors for detecting the radiation under analysis; (2) establishing at least one coincident spectrum corresponding to pairs of events simultaneously detected in both detectors and coming from said ancillary source; and (3) calibrating (for offset correction) said coincident spectrum by using a first energy peak of said spectrum as said first reference energy peak and a second reference energy peak.

Claim 34

Dependent Claim 133 words

Nuclear spectroscopy method for the offset correction of an energy spectrum, made from a signal, emitted by a radiation detector, and containing nuclear events, represented by pulses, whose amplitude is a measure of the energy of the particles, such as gamma rays, collected by said radiation detector, said energy spectrum including at least a first reference energy peak coming from an ancillary nuclear source, comprising the steps of: (1) using at least two detectors for detecting the radiation under analysis; (2) establishing at least one coincident spectrum corresponding to pairs of events simultaneously detected in both detectors and coming from said ancillary source; and (3) calibrating (for offset correction) said coincident spectrum by using a first energy peak of said spectrum as said first reference energy peak and a second reference energy peak.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-06-10	1994-12-10	1995-06-11	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-06-10	1998-12-10	1999-06-11	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-06-10	2002-12-10	2003-06-11	$7700.00	Window Closed / Lapsed

Nuclear spectroscopy signal stabilization and calibration method and apparatus

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