David J.G. Marques, RD51 Mini-week, 4-6 December …...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

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


LIP

Physics Department

University of Coimbra

Coimbra, Portugal

E-mail: [email protected] and [email protected]

mailto:[email protected]

mailto:[email protected]

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


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.


&

STUDY OF ION TRANSPORT PROPERTIES IN NE-CF4


December 2018

Theoretical Background

5

+V

E

E

Microscopically…

5


&



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


&



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

+ ?)


&



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


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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


&


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


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.


&



December 2018

DP-IDC: Components, preliminary tests and system proposal

11


&



December 2018

DP-IDC: Assembly

12


&



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


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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.


&



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


&



December 2018

Thank you!


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


&



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).


&



December 2018

Documents

David J.G. Marques, RD51 Mini-week, 4-6 December …...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