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Transcript of 1 CF4 Scintillation and Aging LIP - Coimbra Luís Margato Andrei Morozov Luís Pereira Margarida...
1
CF4 Scintillation and Aging
LIP - Coimbra
Luís MargatoAndrei Morozov Luís PereiraMargarida FragaFrancisco Fraga
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CF4 Scintillation
CF4 Primary ScintillationCF4 Primary Scintillation
► Produced by ionizing radiation
► Results were presented at Jornadas do LIP 2010 and published [Ref. 1] [Ref.2]
CF4 Secondary ScintillationCF4 Secondary Scintillation
► Light emission associated to electron multiplication induced by a high electric field.
► In order to have a high electric field in a well-defined region of space micropattern structures can be used e.g. MSGCs, GEMs.
CF4 ScintillationCF4 Scintillation
Photon yield for ultraviolet and visible emission from CF4 excited with α-particlesA. Morozov, M.M.F.R. Fraga, L. Pereira, L.M.S. Margato, S.T.G. Fetal, B. Guerard, G. Manzin, F.A.F. FragaNuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volume 268, Issue 9 (2010) 1456-1459.
[Ref. 1]
Effect of electric field on the primary scintillation from CF4A. Morozov, M.M.F.R. Fraga, L. Pereira, L.M.S. Margato, S.T.G. Fetal, B. Guerard, G. Manzin, F.A.F. FragaNuclear Instruments and Methods in Physics Research Section A 628 (2011) 360-363.
[Ref. 2]
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Secondary ScintillationSecondary Scintillation
CF4 Scintillation
For detector design it is For detector design it is critical to know:critical to know:
Emission SpectraEmission Spectra
Light Yield Light Yield
Decay Time of the EmissionDecay Time of the Emission
Light Emission StabilityLight Emission Stability
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
Images of the Sec. Scintillation from a Images of the Sec. Scintillation from a microtrip (readout by a CCD)microtrip (readout by a CCD)
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CF4 Scintillation
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Secondary Scintillation characterizationSecondary Scintillation characterization
Emission Spectra Emission Spectra (all corrections are applied)(all corrections are applied)
CF4 Scintillation
MSGC:MSGC:1- 5 bar CF41- 5 bar CF4
Secondary scintillation in CF4: emission spectra and photon yields for MSGC and GEMA Morozov, L M S Margato, M M F R Fraga, L Pereira and F A F FragaJINST 7 P02008, doi:10.1088/1748-0221/7/02/P02008
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Secondary Scintillation characterizationSecondary Scintillation characterization
Emission Spectra Emission Spectra (all corrections are applied)(all corrections are applied)
CF4 Scintillation
GEM:GEM:1bar CF41bar CF4
GEM: spectra show an apparent increase in the intensity of the emission originating from excited molecules (and a minor decrease in the emission from ions)
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Secondary Scintillation characterizationSecondary Scintillation characterization Light Yield Light Yield (Ph / el ratios)(Ph / el ratios)
CF4 Scintillation
Ph/el ratio as a function of pressure for a fixed MSGC charge gain of ~70; Two MSGCs (designated “M1” and “M2”) were used;
The average values of the ph/el ratios at each pressure are also shown with their full (statistical +systematic) uncertainties.
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
The St707 wide operating temperature range down to room temperature
Once the alloy is activated, reactive molecules such as O2, H2O, N2, CO, CO2 and H2 are adsorbed via a three steps adsorption mechanism: surface dissociation, surface sorption and bulk diffusion.
Purifier SAES St 707 (Custom Assembly)
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Gas Purification SystemGas Purification System
Purifier SAES Microtorr MC1 – 905F
Clean gas cell
Two Types of Purifiers
− SAES St 707 getters (custom assembly)
− SAES MicroTorr MC1-905F
CF4 Scintillation – Gas Aging studies
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Experimental Setup
Time spectra was recorded by a start (Solid State Detector) and stop (PMT) technique
Study performed in the UV (220-450nm) and Visible (450-800nm):
An Am-241 alpha source was used for excitation
PMs were used in Single Photon Counting mode:
UV (220-450nm)
−PMT Photonis XP2020Q (HV=+2000V)−Broadband Filter: Schott UG11
Visible (450-800nm)
−PMT Hamamatsu R1387 (HV=-1170V)−UV-Block Filter: 450 nm cut-off
Study performed in the UV (220-450nm) and Visible (450-800nm):
An Am-241 alpha source was used for excitation
PMs were used in Single Photon Counting mode:
UV (220-450nm)
−PMT Photonis XP2020Q (HV=+2000V)−Broadband Filter: Schott UG11
Visible (450-800nm)
−PMT Hamamatsu R1387 (HV=-1170V)−UV-Block Filter: 450 nm cut-off
CF4 Scintillation – Gas Aging studies
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Effect of small admixtures of N2, O2, Dry Air, to CF4 Effect of small admixtures of N2, O2, Dry Air, to CF4
Visible component is affected by N2, O2 and Dry Air admixtures (different decay times)
Addition of N2, O2 and Dry Air seem to have a negligible effect in the Slope of the UV component
0 10 20 30 40 50 60 70 801
10
100
1000
CF4 (3 bar)
CF4 + 10mbar N
2 (3bar)
CF4 + 10mbar DryAir (3bar)
CF4 + 5mbar O
2 (3bar)
UV
<N
>
Time (ns)
0 20 40 60 80 100 1201
10
100
1000 Visible
~ 15 ns
~ 25 ns CF4 (3bar)
CF4 + 10mbar N
2 (3bar)
CF4 + 10mbar DryAir (3bar)
CF4 + 5mbar O
2 (3bar)
<N
>
Time (ns)
Time spectra (Primary Scintillation)Time spectra (Primary Scintillation)
UV UV VisibleVisible
CF4 Scintillation – Gas Aging studies
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Effect of small admixtures of N2, O2, Dry Air, to CF4 Effect of small admixtures of N2, O2, Dry Air, to CF4
Light output (relative intensity)Light output (relative intensity)
UV UV VisibleVisible
CF4 Scintillation – Gas Aging studies
0 10 20 30 40 50 600.0
0.5
1.0
UV:CF4 (3bar)
UV:CF4 + 10mbarDryAir (3bar)
UV:CF4 + 5mbar O
2 (3bar)
Inte
nsi
ty (
a.u
)
Time (min.)
0 10 20 30 40 50 600.0
0.5
1.0
CF4 (3bar)
CF4 + 10mbar DryAir (3bar)
CF4 + 5mbar O
2 (3bar)
Inte
nsi
ty (
a.u
.)
Time (min.)
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Purification effect of the contaminated CF4 Purification effect of the contaminated CF4 Two examples: Two examples: CF4 contaminated by Araldite CF4 contaminated by Araldite (());; CF4 with an admixture of N2.CF4 with an admixture of N2.
CF4 Scintillation – Gas Aging studies
0 20 40 60 80 100 120
10
100
1000Visible
CF4 (1.5bar)
CF4 + 20mbar N
2 (1.5bar)
Purification: St 707 Purification: MC1-905F
<N
>
Time (ns)0 20 40 60 80 100 120
10
100
1000Visible
CF4 (1.5bar)
CF4 + Araldite Contam. (1.5bar)
Purification: St 707Purification: MC1-905F
<N
>
Time (ns)
Admixture of N2Admixture of N2Contamination with AralditeContamination with Araldite
Time spectra (Visible component)Time spectra (Visible component)
After purification recovery to pure CF4 conditions (both purifiers)
For N2 N2 admixtures MC1MC1 purifier does does not recovernot recover to pure CF4 conditions
(() Araldite Rapid 2012) Araldite Rapid 2012
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Light output (relative intensity)Light output (relative intensity)
CF4 Scintillation – Gas Aging studies
Purification effect of the contaminated CF4 Purification effect of the contaminated CF4 Two examples: Two examples: CF4 contaminated by Araldite;CF4 contaminated by Araldite; CF4 with an admixture of N2.CF4 with an admixture of N2.
0 50 100 150 200 2500.0
0.5
1.0
Visible
Contaminated CF4
Pure CF4
Start Purification
CF4 (1.5 bar)
CF4 + Araldite contaminants (1.5 bar)
(Purification: SAES St 707)CF
4 + Araldite contaminants (1.5 bar)
(Purification: SAES MC1-905F)
Inte
nsity
(a.
u.)
Time (min.)
0 100 200 300 400 500 600 700 800 900 10000.0
0.5
1.0
Vis PMT: CF4+20mbar N
2 (1.5bar)
(MC1 905 and St 707 Purif.)
MC1 "Start"
St 707 "Start"
CF4+20mbar N
2 (1.5bar)
CF4 (1.5bar)
MC1 "Stop"
Inte
nsi
ty (
a.u
.)
Time (min.)
Contamination with AralditeContamination with Araldite Admixture of N2Admixture of N2
Effect of the gas contamination on CF4 primary and secondary scintillationL M S Margato, A Morozov, L Pereira, M M F R Fraga and F A F FragaNuclear Instruments and Methods in Physics Research Section A (in press)http://dx.doi.org/10.1016/j.nima.2011.10.033
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Emission Spectra and ph/el ratios of the Secondary Scintillation Emission Spectra and ph/el ratios of the Secondary Scintillation have been characterized:have been characterized:
Dependence on gain and pressure;
MSGC vs. GEM (1bar);
Gas aging studies:Gas aging studies:
Was shown that a time resolved technique can be used to study CF4 contamination and purification;
The visible emission of primary scintillations is more sensitive to gas impurities than the UV emission;
Aging studies for CF4 Secondary Scintillation have also been performed;
The Purifiers SAES St 707 and MC1-905F show ability to recover contaminated CF4 to fresh filling conditions, but the MC1-905F doesn't remove N2
► Study of the Decay Time of the CF4 Secondary Scintillation Study of the Decay Time of the CF4 Secondary Scintillation is being performedis being performed
CF4 Scintillation – Gas Aging studies
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Thank you for your attention
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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CF4 Primary Scintillation: CF4 Primary Scintillation: Time SpectraTime SpectraCF4 Primary Scintillation: CF4 Primary Scintillation: Time SpectraTime Spectra
Typical effective lifetimesTypical effective lifetimes
Effective lifetimes measured in the absence of electric field are: ~4 – 6 ns for the UV component
and ~8 – 16 ns for the visible component
Both the visible and UV time spectra show no indications of any slow (effective lifetime on the order of 100ns and longer) decay components.
CF4 Primary Scintillation
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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CF4 Scintillation – Gas Aging studies
Time spectra Time spectra (Visible component)(Visible component)
Kapton Contamination: After purification recovery to pure CF4 conditions (both purifiers)
Purifier: SAES St 707Purifier: SAES St 707Purifier : SAES Micro Torr MC1 905Purifier : SAES Micro Torr MC1 905
0 20 40 60 80 100 1201
10
100
1000
Vis: CF4 (1.5bar)
Vis: CF4 (1.5bar) + Kapton
Vis: CF4 (1.5bar) + Kapton (Purif. MicroTorr MC1-905F)
<N
>
Time (ns)0 20 40 60 80 100 120
1
10
100
1000
CF4 (1.5bar)
CF4 (1.5bar) + Kapton (run3)
Purif. SAES St 707
<N
>
Time (ns)
Purification effect of the contaminated CF4 Purification effect of the contaminated CF4 CF4 contaminated by KaptonCF4 contaminated by Kapton
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Secondary scintillation – Experimental SetupSecondary scintillation – Experimental Setup
A MSGC plate (ILL6C) was used for electron multiplication and secondary light production
Anode current read by an electrometer (Keithley 602):
Used to monitor the MSGC charge gain
Rate of coincidences between the charge and light signals:
Relative intensity of the secondary scintillation
Ratio of the coincidence rate to the secondary current:
Secondary scintillation intensity corrected for the gain fluctuations
CF4 Scintillation – Gas Aging studies
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal
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Secondary ScintillationPurification effect on CF4 Purification effect on CF4
0 20 40 60 80 1000
200
400
600
800
1000
CF4 (1 bar)Direct Filling
Filling through Purif. MC1Filling through Purif. St 707@300ºC
Isec
. (pA
)
Time (min.)
0 20 40 60 80 1000
1
2
CF4 (1 bar)
Direct FillingFilling through Purif. MC1Filling through Purif. St 707@300ºC
Lig
ht
ou
tpu
t /
Se
c. E
lect
ron
(a
.u)
Time (min.)
No significant difference in the emission intensity has been observed using these three filling conditions.
CF4 Scintillation – Gas Aging studies
0 20 40 60 80 1000
10
20
30
40
50
CF4 (1 bar)Direct Filling
Filling through Purif. MC1Filling through Purif. St 707@300ºC
Co
inci
den
ce R
ate
(s-1)
Time (min.)
Light outputLight output Anode currentAnode current
Luís Margato ([email protected]) Jornadas LIP, April 21-23, 2012, Lisbon, Portugal