CN104362068B - Method for adjusting gain of electron multiplier - Google Patents
Method for adjusting gain of electron multiplier Download PDFInfo
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- CN104362068B CN104362068B CN201410657159.0A CN201410657159A CN104362068B CN 104362068 B CN104362068 B CN 104362068B CN 201410657159 A CN201410657159 A CN 201410657159A CN 104362068 B CN104362068 B CN 104362068B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J43/00—Secondary-emission tubes; Electron-multiplier tubes
- H01J43/04—Electron multipliers
- H01J43/30—Circuit arrangements not adapted to a particular application of the tube and not otherwise provided for
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Abstract
The invention relates to a method for adjusting the gain of an electron multiplier. The method for adjusting the gain of the electron multiplier comprises the steps that the electron multiplier is loaded with an initial voltage V<initial 1>, the voltages loaded onto the electron multiplier are adjusted according to a step length delta V<1>, the signal of shot noise generated on the electron multiplier at each voltage is recorded, along with changes of the voltages loaded onto the electron multiplier, the voltage, loaded onto the electron multiplier, corresponding to the signal, obtained for the first time, larger than a preset first threshold value is the first voltage, the voltage, loaded onto the electron multiplier, corresponding to the signal, obtained for the first time, larger than a preset second threshold value is the second voltage, the target voltage corresponding to the optimum gain is obtained according to the first voltage and the second voltage, the target voltage value is loaded onto the electron multiplier, and the gain is adjusted to the optimal value. The method for adjusting the gain of the electron multiplier has the advantages of being high in efficiency, low in cost, convenient and fast to execute and the like, and operation is easy to carry out.
Description
Technical field
The present invention relates to a kind of method adjusting electron multiplier gain, it is mainly used in mass detector.
Background technology
Mass spectrograph generally uses electron multiplier as detector, for amplifying from ion trap analyzer outgoing
Current ion signal.Generally, the gain of electron multiplier all can control 105, but it is as the increasing of use time
Plus or some other state change, the gain of electron multiplier can change, at this time, it may be necessary to pass through
Adjust the high pressure being carried on electron multiplier to adjust gain so that gain is maintained at 105Left and right, thus protect
Demonstrate,prove stablizing of mass signal intensity.At present, adjust gain method mainly have following two：
1st, lead to gas method
It is passed through certain density calibrating gas in mass spectrometric vacuum chamber it is known that this calibrating gas is examined in mass spectrum
Survey the response made in device, by the response now obtaining compared with fixing response, both sizes
Reflect the change in gain of electron multiplier.Adjust electron multiplier on load voltage so that response with
Fixed value is identical, by the gain control of multiplier in a stable level.But adjusted by the method
Gain existing defects, that is,：The method directly calibrating gas is passed through in vacuum chamber, leads to the substantial amounts of suction of gas
It is attached to the interior surface of vacuum chamber, cause there is gas ion, baseline all the time in mass spectrum baseline in a period of time
Noise increases, and sensitivity decrease typically cannot be carried out sample test in two hours after adjustment.
2nd, squeeze into electron stream method
The electron stream of known strength is beaten on the receiving terminal of electron multiplier, then measures its output circuit
Size can obtain the gain of electron multiplier.By adjusting the voltage on electron multiplier, by gain control
105Level on.Gain is adjusted by the method, there is following defect：The electronics of known strength to be obtained
Stream needs complex device, simultaneously need to electron multiplier is taken out from mass spectrograph carrying out outside survey
Examination, operation inconvenience, less efficient.
Content of the invention
In order to solve above-mentioned deficiency of the prior art, the invention provides a kind of simple to operate, convenient, high
The electron multiplier gain adjusting method therefore of effect.
For achieving the above object, the present invention adopts the following technical scheme that：
A kind of gain adjusting method therefore, comprises the following steps：
Initial voltage V is loaded on electron multiplierFirst 1, according to step delta V1Regulation is carried in electron multiplier
On voltage, under each voltage, on recorded electronic multiplier produce shot noise signal, with
It is carried in the change of the voltage on electron multiplier, the signal pair more than default first threshold obtaining first
The voltage being carried on electron multiplier answered be first voltage, obtain first more than default Second Threshold
The corresponding voltage being carried on electron multiplier of signal be second voltage, according to described first voltage and the
Two voltages, draw the target voltage of corresponding optimum gain, and target voltage values are carried on electron multiplier,
By gain-adjusted to optimal.
Further, described target voltage amplitude is between described first voltage and second voltage.
Preferably, described target voltage takes the mean value of described first voltage and second voltage.
Optimality criterion voltage can be set based on experience value it is also possible to be obtained by testing standard sample, that is, divide
The test result to standard sample for the analysis, selects the corresponding electricity being carried on electron multiplier during signal to noise ratio highest
Pressure, and as optimality criterion voltage.
Select the first normal voltage and the second normal voltage in optimality criterion voltage both sides respectively, then according to the
One normal voltage and the second normal voltage obtain first threshold and Second Threshold.
Further, the basis of design of described first threshold and Second Threshold is：
Primary standard voltage V is loaded on electron multiplierJust, adjust according to step delta V and be carried in electron multiplication
Voltage on device, under each voltage, the signal of the shot noise that recorded electronic multiplier produces, plus
The voltage being loaded on electron multiplier is that during the first normal voltage, corresponding signal value is first threshold, is carried in
Voltage on electron multiplier is that during the second normal voltage, corresponding signal value is Second Threshold.
Further, described first threshold and Second Threshold can also obtain based on experience value.
Further, the first normal voltage and the second normal voltage are selected according to described optimality criterion voltage.
Preferably, described optimality criterion voltage takes the average of described first normal voltage and the second normal voltage
Value.
Preferably, loading initial voltage VFirst 1Amplitude be more than primary standard voltage VJustAmplitude.
Preferably, described step delta V1More than described step delta V.
Further, described signal is intensity and the frequency of shot noise.
When certain voltage is loaded on electron multiplier, some pulse signals can be randomly generated, these signal quilts
Referred to as shot noise.It is found through experiments, the gain of the intensity of shot noise and the frequency of occurrences and multiplier is just
Correlation, whether the gain that therefore can judge multiplier by measuring the intensity of shot noise with occurrence number is located
About 105Level on.
The present invention compared with prior art has the advantages that：
1st, efficiency high, low cost
Electron multiplier adjusts and need not lead to outside gas, will not be detained, when not needing in mass spectrum vacuum chamber
Between wait noise reduction, can be used after regulation, efficiency high；And only need itself to adjust it is not necessary to outside
Device power-assisted, low cost.
2nd, simple to operate, convenient
Electron multiplier is adjusted not to be needed to lead to certain density calibrating gas it is not required that the device of external complex
Produce the electron stream of certain known strength, less need for electron multiplier to take out vacuum chamber, simple to operate,
Convenient, save the time.
Brief description
Fig. 1 is the corresponding gain adjusting method therefore flow chart of embodiment 2.
Specific embodiment
Embodiment 1
A kind of gain adjusting method therefore, comprises the following steps：
Initial voltage V is loaded on electron multiplierFirst 1, according to step delta V1Regulation is carried in electron multiplier
On voltage, under each voltage, on recorded electronic multiplier produce shot noise signal, with
It is carried in the change of the voltage on electron multiplier, the signal pair more than default first threshold obtaining first
The voltage being carried on electron multiplier answered be first voltage, obtain first more than default Second Threshold
The corresponding voltage being carried on electron multiplier of signal be second voltage, according to described first voltage and the
Two voltages, draw the target voltage of corresponding optimum gain, and target voltage values are carried on electron multiplier,
By gain-adjusted to optimal.
The amplitude of described target voltage is between described first voltage and second voltage.
Further, described signal is intensity and the frequency of shot noise.
When certain voltage is loaded on electron multiplier, some pulse signals can be randomly generated, these signal quilts
Referred to as shot noise.It is found through experiments, the gain of the intensity of shot noise and the frequency of occurrences and multiplier is just
Correlation, whether the gain that therefore can judge multiplier by measuring the intensity of shot noise with occurrence number is located
About 105Level on.
Set first threshold and Second Threshold, by recording the signal of shot noise, with first threshold and second
Corresponding first voltage and second voltage can also determine threshold value respectively respectively.Then described target voltage gets final product root
Obtain according to described first voltage and second voltage.
Further, described target voltage amplitude is between described first voltage and second voltage.
Preferably, described target voltage takes the mean value of described first voltage and second voltage.
Optimality criterion voltage can be set based on experience value it is also possible to be obtained by testing standard sample, that is, divide
The test result to standard sample for the analysis, selects the corresponding electricity being carried on electron multiplier during signal to noise ratio highest
Pressure, and as optimality criterion voltage.Optimality criterion voltage both sides respectively select the first normal voltage and
Second normal voltage, then obtains first threshold and the second threshold according to the first normal voltage and the second normal voltage
Value.
Further, the basis of design of described first threshold and Second Threshold is：
Primary standard voltage V is loaded on electron multiplierJust, adjust according to step delta V and be carried in electron multiplication
Voltage on device, under each voltage, the signal of the shot noise that recorded electronic multiplier produces, plus
The voltage being loaded on electron multiplier is that during the first normal voltage, corresponding signal value is first threshold, is carried in
Voltage on electron multiplier is that during the second normal voltage, corresponding signal value is Second Threshold.
Described first threshold and Second Threshold can also obtain based on experience value.
The amplitude of described optimality criterion voltage is between described first normal voltage and the second normal voltage.
Further, the first normal voltage and the second normal voltage are selected according to described optimality criterion voltage.
Preferably, described optimality criterion voltage takes the average of described first normal voltage and the second normal voltage
Value.
Primary standard voltage VJustWith loading initial voltage VFirst 1Can identical it is also possible to different；
Preferably, loading initial voltage VFirst 1Amplitude be more than primary standard voltage VJustAmplitude.
Voltage step size Δ V during actual adjustment electron multiplier gain1Can be with setting first threshold and the second threshold
Step delta V that value is identical it is also possible to different.
Preferably, described step delta V1More than described step delta V.
Electron multiplier adjusts and need not lead to outside gas, will not be detained, when not needing in mass spectrum vacuum chamber
Between wait noise reduction, can be used after regulation, efficiency high；And only need itself to adjust it is not necessary to outside
Device power-assisted, low cost.
Electron multiplier is adjusted not to be needed to lead to certain density calibrating gas it is not required that the device of external complex
Produce the electron stream of certain known strength, less need for electron multiplier to take out vacuum chamber, simple to operate,
Convenient, save the time.
Embodiment 2
The present embodiment is the application examples of embodiment 1.
Present embodiments provide a kind of electron multiplier gain adjusting method therefore, be applied to gas chromatography-mass spectrography
Instrument, comprises the following steps：
Refer to Fig. 1, a kind of gain adjusting method therefore, comprise the following steps：
Initial voltage V is loaded on electron multiplierFirst 1=-1000V, according to step delta V1=-100V increase adds
It is loaded in the voltage on electron multiplier, under each voltage, the shot that recorded electronic multiplier produces is made an uproar
The signal of sound, with the increase of the voltage being carried on electron multiplier, obtain first more than default
The corresponding voltage being carried on electron multiplier of the signal of one threshold value is first voltage, and obtain first is more than
The corresponding voltage being carried on electron multiplier of the signal of default Second Threshold is second voltage, according to institute
State first voltage and second voltage, draw the target voltage of corresponding optimum gain, target voltage values are carried in
On electron multiplier, by gain-adjusted to optimal；
The first threshold of the present embodiment is：Shot noise intensity is 1, and frequency is to occur 3 times in 20 seconds；
Second Threshold is 3 for shot noise intensity, and frequency is to occur 3 times in 20 seconds.
In the present embodiment, first voltage is -1200V, and second voltage is -1500V, then target voltage is -1350V；
The Voltage Cortrol being carried on electron multiplier is target voltage -1350V so that gain-adjusted is to
Good.
The first threshold of the present embodiment and Second Threshold are and are obtained by empirical value.
Embodiment 3
Present embodiments provide a kind of gain adjusting method therefore, different from the gain adjusting method therefore in embodiment 2
It is：
The present embodiment adjusts the initial voltage V loading during gainFirst 1=-1600V, step delta V1=100V.Specifically
Adjust gain according to following steps：
Initial voltage V is loaded on electron multiplierFirst 1=-1600V, according to step delta V1=100V reduces loading
Voltage on electron multiplier, under each voltage, the shot noise of generation on recorded electronic multiplier
Signal, with the reduction of the voltage being carried on electron multiplier, obtain first more than default first
The corresponding voltage being carried on electron multiplier of the signal of threshold value be first voltage, obtain first more than pre-
If Second Threshold the corresponding voltage being carried on electron multiplier of signal be second voltage, according to described
First voltage and second voltage, draw the target voltage of corresponding optimum gain, target voltage values are carried in electricity
On sub- multiplier, by gain-adjusted to optimal；
The first threshold of the present embodiment is：Shot noise intensity is 3, and frequency is to occur 3 times in 20 seconds；
Second Threshold is 1 for shot noise intensity, and frequency is to occur 3 times in 20 seconds.
In the present embodiment, first voltage is -1500V, and second voltage is -1200V, then target voltage is -1350V；
The Voltage Cortrol being carried on electron multiplier is target voltage -1350V so that gain-adjusted is to
Good.
The first threshold of the present embodiment and Second Threshold are and are obtained by empirical value.
Embodiment 4
Present embodiments provide a kind of gain adjusting method therefore, different from the gain adjusting method therefore in embodiment 2
It is：
The first threshold of the present embodiment obtains according to the instrument mensure related in optimum gain with Second Threshold.
Obtain with specific reference to following steps：
Primary standard voltage V is loaded on electron multiplierJust=-1100V, increases according to step delta V=-50V and adds
It is loaded in the voltage on electron multiplier, under each voltage, the shot that recorded electronic multiplier produces is made an uproar
The signal of sound, with the increase of the voltage being carried on electron multiplier, in the corresponding optimal mark of optimum gain
The first normal voltage and the second normal voltage are selected in quasi- voltage both sides, and the voltage being carried on electron multiplier is
During the first normal voltage, corresponding signal value is first threshold, and the voltage being carried on electron multiplier is second
During normal voltage, corresponding signal value is Second Threshold：
In the present embodiment, optimum gain corresponding optimality criterion voltage is -1300V, selectes the first normal voltage
For -1150V, selecting the second normal voltage is -1450V, then the corresponding first threshold of the first normal voltage is：
Shot noise intensity is 2, and frequency is to occur 3 times in 20 seconds；The corresponding Second Threshold of second normal voltage is
Shot noise intensity is 4, and frequency is to occur 3 times in 20 seconds.
Above-mentioned embodiment should not be construed as limiting the scope of the invention.The key of the present invention is：Root
According to the signal of shot noise, set dependent thresholds, target voltage is worth to according to the corresponding voltage of dependent thresholds
Value, then target voltage values are carried on electron multiplier adjust gain to optimal.Without departing from present invention essence
In the case of god, any type of change that the present invention is made all should fall under the scope of the present invention.
Claims (9)
1. a kind of gain adjusting method therefore, comprises the following steps：
Initial voltage V is loaded on electron multiplierFirst 1, according to step delta V1Regulation is carried in electron multiplier
On voltage, under each voltage, on recorded electronic multiplier produce shot noise signal, with
It is carried in the change of the voltage on electron multiplier, the signal pair more than default first threshold obtaining first
The voltage being carried on electron multiplier answered be first voltage, obtain first more than default Second Threshold
The corresponding voltage being carried on electron multiplier of signal be second voltage, according to described first voltage and the
Two voltages, draw the target voltage of corresponding optimum gain, and target voltage values are carried on electron multiplier,
By gain-adjusted to optimal.
2. gain adjusting method therefore according to claim 1 it is characterised in that：Described target voltage amplitude exists
Between described first voltage and second voltage.
3. gain adjusting method therefore according to claim 2 it is characterised in that：Described target voltage takes described
First voltage and the mean value of second voltage.
4. gain adjusting method therefore according to claim 1 it is characterised in that：Described first threshold and second
The basis of design of threshold value is：
Primary standard voltage V is loaded on electron multiplierJust, adjust according to step delta V and be carried in electron multiplication
Voltage on device, under each voltage, the signal of the shot noise that recorded electronic multiplier produces,
The first normal voltage and the second normal voltage are selected in optimality criterion voltage both sides, are carried on electron multiplier
Voltage is that during the first normal voltage, corresponding signal value is first threshold, is carried in the voltage on electron multiplier
It is Second Threshold for signal value corresponding during the second normal voltage, described optimality criterion voltage is signal to noise ratio highest
When the corresponding voltage being carried on electron multiplier.
5. gain adjusting method therefore according to claim 4 it is characterised in that：Described first normal voltage and
The value preset of the second normal voltage is the twice of described optimality criterion magnitude of voltage.
6. the gain adjusting method therefore according to claim 4 or 5 it is characterised in that：Described optimality criterion electricity
Pressure is obtained by testing standard sample：The test result to standard sample for the analysis, selects during signal to noise ratio highest pair
The voltage being carried on electron multiplier answered, and as optimality criterion voltage.
7. gain adjusting method therefore according to claim 4 it is characterised in that：Load initial voltage VFirst 1
Amplitude be more than primary standard voltage VJustAmplitude.
8. gain adjusting method therefore according to claim 4 it is characterised in that：Described step delta V1More than institute
State step delta V.
9. gain adjusting method therefore according to claim 1 it is characterised in that：Described signal is shot noise
Intensity and frequency.
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| US3898452A (en) * | 1974-08-15 | 1975-08-05 | Itt | Electron multiplier gain stabilization |
| EP1405055A4 (en) * | 2001-05-25 | 2007-05-23 | Analytica Of Branford Inc | Multiple detection systems |
| CN101145816A (en) * | 2007-09-05 | 2008-03-19 | Ut斯达康通讯有限公司 | Method and module for quickly adjusting automatic gain control value |
| US7741909B2 (en) * | 2008-04-14 | 2010-06-22 | Mediatek Singapore Pte Ltd | Linear-in-dB variable gain amplifier |
| FR2941065B1 (en) * | 2009-01-12 | 2011-02-11 | Alcatel Lucent | DEVICE FOR MEASURING AND PROCESSING A HIGH DYNAMIC INPUT SIGNAL, LEAK DETECTOR AND CORRESPONDING MEASUREMENT AND PROCESSING METHOD |
| CN101750622B (en) * | 2009-12-28 | 2011-07-06 | 中国人民解放军国防科学技术大学 | Accelerated degradation test method of multistage separation type dynode electron multiplier |
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Effective date of registration: 20160826 Address after: Hangzhou City, Zhejiang province Binjiang District 310052 shore road 760 Applicant after: Focused Photonics (Hangzhou) Inc. Applicant after: Hangzhou Pu Yu development in science and technology Co., Ltd Address before: Hangzhou City, Zhejiang province Binjiang District 310052 shore road 760 Applicant before: Focused Photonics (Hangzhou) Inc. |
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