2015 D Lascar Postdoctoral Fellow TRIUMF How do you relate time to mass How do you trap ions What is going on in a Penning trap Time of Flight conversion Outline Oct 9 2015 SFU Nuclear Chemistry Mass 2 ID: 647346
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Slide1
Mass Measurements
Lecture 2 – October 9, 2015
D. Lascar | Postdoctoral Fellow | TRIUMFSlide2
How do you relate time to mass?How do you trap ions?
What is going on in a Penning trap?Time of Flight conversion
Outline
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
2Slide3
Time is the physical quantity we can measure most precisely
For this clock:We can do better than
When making a precision measurement, the goal is to measure time (frequency)
For next class:
How can you relate a time (frequency) measurement to mass?
When last we left this…
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
3
Slide4
Put it back in a magnetic field
This time for longer.Long enough that it can complete multiple orbits.
How do you relate time to mass?
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
4
x x x x x x x x x x x x
x x x x x x x x x x x x
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+
Slide5
Put it back in a magnetic field
This time for longer.Long enough that it can complete multiple orbits.
How do you relate time to mass?
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
5
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
+
Slide6
Put it back in a magnetic field
This time for longer.Long enough that it can complete multiple orbits.Can’t come in perpendicularly
Radius is a function of initial energy but you’ll never do better than a semicircleHow to get a full orbit?
How do you relate time to mass
?
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
6
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
+Slide7
Put it back in a magnetic field
This time for longer.Long enough that it can complete multiple orbits.
Send it along a uniform
-field
How do you relate time to mass
?
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
7
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
+
Any perpendicular component will induce an oscillation
+Slide8
The ion will keep moving along.
Doesn’t give us much time to study it.What should we do?
What about the axial direction?
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
8
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
+
+Slide9
Create a potential well.
All you need are a couple of electrodes
What about the axial direction?
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
9
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
x x x x x x x x x x x x
+
+
Slide10
A Penning Trap
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
10
Electrodes create
an axial quadrupole trapping potential
The potential
repels
in the radial direction but B takes care of that
Quadrupole potential created by making the electrodes conform to 2 hyperboloids of revolution.Slide11
A Penning Trap
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
11
Electrodes create
an axial quadrupole trapping potential
The potential
repels
in the radial direction but B takes care of that
Quadrupole potential created by making the electrodes conform to 2 hyperboloids of revolution.
TITAN at TRIUMFSlide12
A Penning Trap
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
12
Electrodes create
an axial quadrupole trapping potential
The potential
repels
in the radial direction but B takes care of that
Quadrupole potential created by making the electrodes conform to 2 hyperboloids of revolution.
TITAN at TRIUMF
The CPT at ArgonneSlide13
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
13Slide14
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
14Slide15
Ions are trapped in 3 dimensions
Now you can study themTrapping Ions
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
15Slide16
Storage of ions in a Penning trap
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
16Slide17
Energy Conversion
10/12/2012
Northwestern University - Thesis Defense
Magnetic field lines outside the Penning trap
Ions from the Penning trap
Orbital
Energy
Linear
Energy
Channeltron
TOF
Detection
17
c
ExcitationSlide18
Unknown:
Time of Flight (arb units)
Slide courtesy of J. Van
Schelt
Sample
ToF
Spectrum
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
18
Frequency (kHz)
133
CsSlide19
Unknown:
f
c
=663,104.706(3) Hz (
560 eV/c
2
)
Time of Flight (arb units)
Slide courtesy of J. Van
Schelt
Sample
ToF
Spectrum
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
19
Frequency (kHz)
For 1 s excitation, Width ~1Hz =
Δν
Δ
m ≈ 200
keV
/c
2
133
CsSlide20
System Stability
10/12/2012
Northwestern University - Thesis Defense
20
663,109.086(8) Hz
Slide21
Questions – In class then homework
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
21Slide22
Larger image for your convenience
Oct 9, 2015
SFU Nuclear Chemistry - Mass 2
22Slide23