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David J.G. Marques, RD51 Mini-week, 4-6 December 2018
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT
CHAMBER &
STUDY OF ION TRANSPORT PROPERTIES IN
NE-CF4 MIXTURES
December 2018
David J.G. Marques, M.A.G. Santos, A.F.V. Cortez, R. Veenhof,
P. Colas, P.N.B. Neves, F.P. Santos, C.A.N. Conde, F.I.G.M. Borges
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
LIP
Physics Department
University of Coimbra
Coimbra, Portugal
E-mail: davidmarques_12@hotmail.com and andre.cortez@coimbra.lip.pt
Contents
1. Introduction and motivation
2. Theoretical background
3. Positive ion mobility in gaseous mixtures of
interest (P)
a. Experimental system and
techniques
b. (A review on) Ion mobility in pure
Ne and CF4
c. Ion mobility in Ne-CF4
3
4. Development of the DP-IDC
a. Working principle and design proposal
b. Components, preliminary tests and
system proposal
c. First results
d. Limitations
5. Conclusions and Future work
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4December 2018
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
Introduction and motivation
4
Sig
nal A
mpl
ituded
+HV
Time
Gaseous Radiation
Detectors
Ion Mobility
Spectroscopy
Time projection
Chamber
Powerful tool in high energy and nuclear physics.
Future Linear Collider TPC (LCTPC)
Negative Ion Time
Projection Chamber
Rare event physics searches• Neutrinoless beta decay (0νββ)• Dark matter (WIMPs)Astrophysics• Polarimetry
Technique that aims at identifying ionizedmolecules in a gas based on their mobility in acarrier buffer gas.
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
Theoretical Background
5
+V
E
E
Microscopically…
5
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
Experimental system and techniques
6
Xenon UV flash lamp10Hz, <500ns
Charge Pre-amplifier
DigitalOscilloscope
GEM
E E
Frisch Grid
Frisch Grid Frisch Grid
CsI
P.N.B. Neves et al. 2009
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
0
50
100
150
200
0 50 100 150 200 250
Sig
nal am
pli
tud
e (m
V)
Drift time (ms)
3rd prototype: typical ion pulse
A1
A2
t1 t2
UV Flash
signal
Argon
p = 7.039 Torr
E/N = 30 Td
Ar2+
Ar+
XXX
7
Xenon UV flash lamp10Hz, <500ns
Charge Pre-amplifier
DigitalOscilloscope
Frisch Grid• Subtract the background to
the signal• Identify possible peaks• Fit Gaussian curves to the
spectrum obtained
peaks centroids
After the signal and the background were recorded…
K01 = 1.57 cm2V-1s-1 (Ar+ ?)K02 = 1.92 cm2V-1s-1 (Ar2
+ ?)
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
(A review on) Ion mobility in pure Ne and CF4
8
CF3+E/N = 15 Td
P = 8 Torr
VGEM = 25 V
d d
• One peak (below 8 Td) - Ne2+
• Two peaks present (between 8 and 12 Td)• One peak (above 12 Td) - Ne+
Reactions:
Ne+ + 2Ne Ne2+ + Ne
Ne+ + Ne Ne + Ne+ K01 ~ 4.4 cm2V-1s-1 Ne+
K02 ~ 6.2 cm2V-1s-1 Ne2+
Appearance Energies21.56 eVNe+
Reactions:CF3
+ + 2CF4 CF3+. (CF4) + CF4
Appearance Energies15.0 eV19.0 eV22.3 eV23.1 eV
CF3+
CF2+
CF+
F+
Possibility of Cluster Formation(Pressure dependent)
• One peak present
K01 ~ 1.10 cm2V-1s-1CF3+
P.N.B. Neves et al. 2011
Ion mobility in pure Ne Ion mobility in pure CF4
M.A.G. Santos et al. 2018
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
0
2
4
6
8
0.2 0.3 0.4 0.5
Sign
al a
mp
litu
de
(mV
)
Drift time (ms)
5 15 25 35 45 55 65 75 85 95
0
0.2
0.4
0.6
0.8
1
5 36 64 95
1/K
0(c
m-2
.V.s
)
Ne %
Blanc's Law prediction for CF3+
Blanc's Law prediction for Ne+
Blanc's Law prediction for Ne2+
Data for 15 Td
Data for 20 TdNe2
+
Ne+
CF3+
Ion mobility in Ne-CF4
9
• Cross section.• Presence of CF4 in mixtures
with Ne leads to the sameion as in pure CF4.
Only one peak for 15 Td
Ions move slower with thepresence of CF4.
Behaviour well described byBlanc’s law and Langevin theory.Amplitude rises until 90% of Ne
Increasing pressure may lead to the formation of cluster(about 10% slower than CF3+)
(Charge Transfer Reaction)
Ne+ + CF4 CF3+ + Ne + F
Prevents the
formation of
Ne+.
80% Ne E/N = 15 Td
P = 8 Torr
VGEM = 25 V
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
0
2
4
6
8
0.5 0.6 0.7 0.8Sign
al a
mp
litu
de
(mV
)
Drift time (ms)
E/N = 15 Td
P = 8 Torr
VGEM = 25 V
20% Ne
December 2018
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
DP-IDC: Working principle and design proposal
10
Dual Polarity – Ion Drift Chamber
Allows to:
study the transport properties ofnegative ions in gases, inaddiction to the study of positiveions;
vary the drift distance.
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
DP-IDC: Components, preliminary tests and system proposal
11
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
DP-IDC: Assembly
12
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
DP-IDC: First results
13
*Test gases chosen both by their availability and their known mobility lower than the upper limit of the mobility possible to be measured.
**Tests will follow in the next couple of months to solve these issues.
1. One peak clearly visible in bothspectra, as expected. A long tail andtwo smaller peaks are also visible.
2. Measured mobility about 40% lowerthan in previous work.
• No noticeable signal for:• VGEM = 25 V & E/N < 30 Td• VGEM = 35 V & E/N < 20 Td
• High and unstable electrical noise (6-10 mV).
• Lamp pulse 200 time wider thanexpected.
Solutions:• reducing the length of the cables
between the pre-amplifier and thecollection feedthrough by
• insuring a stable and single groundacross the detector.
p = 8 TorrE/N = 30 TdVGEM = 35 V
p = 8 TorrE/N = 30 TdVGEM = 35 V
Pure N2
Pure CF4
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
DP-IDC: Limitations
14
Electric field
d
Residual gas
Due to outgassing, to the gas non-purity and minimum residual vacuum.In the present installation:
Lamp induced
Teflon spacers
Mean thermal expansion of Teflon and thermal expansioncoefficients at a given temperature vary a lot in the range ofthermal temperatures leading to variations of the order of 0.1mm in the drift distance.*Also, explains why the first double grid prototype failed.
Residual vacuum > 4.89×10-3 TorrConductance < 0.012 l/s
Frequency of the pulses
0.1 s Max. Mob.0.012 cm2V-1s-1
Expected pulse duration
0.5 µs Theor. Min. Mob.2481 cm2V-1s-1
Experimental pulse duration
0.1 ms Exp. Min. Mob.12.4 cm2V-1s-1
• Variations on the mobility of about 23% in half biased mode and of 2% in full biased modes;
• Can lead to lose of signal in half biased mode due to diffusion.
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
Conclusions
15
On the ion mobility On the DP-IDC Future work
dd d• At higher pressures, the
distribution of the final ionsmay differ, however theseaccurate ion mobilitymeasurements have beenconsistently in accordancewith the ones obtained athigher pressures (Kalkan etal. 2015).
• The ion mobility in variousmixtures of interest.
• The mobility values areconsistent with thetheoretical ones given byBlanc’s law using Langevin’stheory, following CF3+ ions.
• The DP-IDC was designed,constructed, preliminarilytested and assembledsuccessfully;
• First tested revealed pooraccuracy but goodprecision;
• Still some problems shouldbe addressed, specially inwhat concerns theuniformity of the electricfield.
• Pursuit the investigation onthe mobility of ions indifferent gas mixtures ofinterest for TPCs andNITPCs:
Ne-iC4H10
Xe-iC4H10
SF6
CS2
O2
N2OCH3NO2
SF6-CH4
SF6-C2H6
CS2-CH4
CS2-C2H6
Xe-SF6
Xe-CS2
CO2-CH3NO2
Ne-CO2-CH3NO2
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
Thank you!
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
17
d
GEM VoltageReaction Time
• Maximum energy gained by electrons.• Primary ions possible to be formed.
Possible Reactions
dIons formed through reactions of the primary ions with neutral atoms or molecules from the medium.
Universal decay law
Rg (pure)
Rg + e -> Rg+ + 2e
Select Most Probable Ions d
Used to calculate the variation of the concentration of a specific ion in a mixture.
Rg + Rg+ -> X+ + Yk
• Identification the possible ions present.
• Identification the possible ions present.
Used to calculate the mobility of an ion in a gas mixture.
17
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
XXX
18
d
Langevin Limit
Blanc’s Law
m – reduced massa – neutral polarizability
Used to calculate the mobility of an ion in a gas mixture.
To determine the mobility of an ion within a gas (not the parent).
Experimental Ion Mobility Values
Theoretical Mobility Values
dMobility of an ion within his parent gas (if known).
DEVELOPMENT OF A DUAL-POLARITY ION DRIFT CHAMBER
&
STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4
David J.G. Marques, RD51 Mini-week, 4-6 December 2018
December 2018
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