Further studies on straw drift tubes for the PANDA Forward Tracker
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Transcript of Further studies on straw drift tubes for the PANDA Forward Tracker
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 1
A.Kashchuk([email protected])
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 2
Near-end FEE- printed circuit board
Anode wire
Schematic view of the straw drift tube with 2 springs ‘a la COSY-TOF’
providing electrical contact to Cathode
Far-end
Elegant light-weight solution,
What quality of the electrical contact ?Aging ?What inductance ?What other problems ?
08 September 2009 3A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg
ButBut
Gas gain uniformity along straw
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 4
Wire eccentricity or sagittaincreases gas gain
20%
(presented in Torino meeting)
Fe-55 scanner
1%
New measurements on 75-cm straw tubes
y = -0.0562x2 + 2.4517x + 23.501
R2 = 0.9638
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30 35 40
Point number along straw (40cm, step 1cm)
Fe-
55 p
eak
po
siti
on
(m
V)
40%
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 5
It seems (as shown below),a sagitta is an intrinsic feature of the straw tube with 2 springs and even one (!)
Mylar tubes with wall thickness 30µmAnode wire diameter 20µmCathode diameter 10mm with metal thickness 300Å=30nmExternal layer with metal thickness 300Å=30nmGas mixture Ar(90%)/CO2(10%) P=2000mb absolute at V=1550V
No sagitta without spring No sagitta without spring No puzzles anymore No puzzles anymore
Measurements become reproducible, etc.Measurements become reproducible, etc.
0
10
20
30
40
50
60
70
80
90
100
110
120
0 5 10 15 20 25 30 35 40
Point number along straw (40cm, step 1cm)
Fe-
55 p
eak
po
siti
on
(m
V)
#003 Copper w/o spring
#004 Aluminum w/o spring
2%
2%
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 6
30%-sagitta simulated by force 8.7g applied to the far-end
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 7
F
Calculations by Vito Carassiti
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0 3.43E -01 0.686 1.71 5.14
Displa c e mnt (mm)
Lo
ad (
N)
LOAD (N) DISPLACEMENT (mm) REACTION (N) K (N/mm)
0 0 0 0
0.02 3.43E-01 0.05733 5.83E-02
0.04 0.686 0.11466 5.83E-02
0.1 1.71 0.28665 5.85E-02
0.3 5.14 0.86 5.84E-02
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 8
Load
Reaction Force
Bending MomentumBending Momentum
Counting characteristics without springs on X-rays Fe-55 Copper straw #003
0200400600800
1000120014001600180020002200240026002800300032003400
1050 1150 1250 1350 1450 1550 1650 1750
HV (V)
Co
un
t F
e-5
5 (
Hz)
Center #003 Fe-55 close to straw
16cm to near-end
16cm to far-end
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 9
~430V
Note:Difference in countson plateau are due to distance variations from the source to straw
Counting characteristics without springs on X-rays Fe-55 Aluminum straw #004
0200400600800
1000120014001600180020002200240026002800300032003400
1050 1150 1250 1350 1450 1550 1650 1750
HV (V)
Co
un
t F
e-5
5 (
Hz)
Al #004 center at Th=970mV
16cm to near-end
16cm to far-end
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 10
~460V
Note:Difference in countson plateau are due to distance variations from the source to straw
4 characteristic regions
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 11
1
23
4
?
ElectronicsThreshol
d
Variations of the gas composition
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 12
CO2(100%)CO2(100%)
×7×7
Ar/CO2(10%)Ar/CO2(10%)
Pure Ar – the lowest electron drift velocity, but no quenching without CO2
450V 600V
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 13
Ar(90%)CO2(10%)Electron drift velocity ~ 40µm/ns – the upper limit to get needed space resolution
Note: Atlas MDTAr(93)CO2(7%) at 3barNo agingHigh rate effect (!)
Baseline mixture
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 14
VEparametersfitsDiethorn
constRdensitygasT
p
R
radiicathodeanodeba
Eab
a
VG
a
bV
V
gas
,:'
)(1
,,
)(ln
min
ln
2ln
00min
Compare spectra with/without springs HV=1600V at P=1000mb (2000mb absolute)
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 15
Fe-555.9keV
3keV
Fe-555.9keV
3keV
FWHM=15%FWHM=15% FWHM=25%FWHM=25%
Gas gain measured vs. HVby peak position of 5.9keV (Fe-55)
7.2100 VdV
dG
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 16
Assuming 17% charge collection by the FE-amplifierat P=2000mb absolute and T=295K
5.9keV
50000)1600( VG
VVcm
kVE 32;20min
Gas gain vs. P at HV=1550V
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 17
%24100dp
dG
B
p
AG
Note: Electron drift velocity is proportional to ratio E/PP reduction increases velocity reducing spatial resolution – bad (!)bad (!)
Needed gas gain
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 18
Note1:IfENC=3000eThmin=18000e=>4p.e.(~4% inefficiency)
Then needed gas gainGmin=38000ln(G)=10.5
Using Diethorn’s fitHVmin~1550V
HVmin~1420V
HVmin~1550V
Note2:Either HV or overpressurecan be used for gas gain stabilizationG(E/p)=constto compensateatmospheric pressure variationsand keep constantefficiency and spaceresolution
and more to have better time-space resolution
Compare HV-plateau at overpressure 500mb and 1000mb
0200400600800
1000120014001600180020002200240026002800300032003400
1050 1150 1250 1350 1450 1550 1650 1750
HV (V)
Co
un
t F
e-5
5 (
Hz)
Al #004 center at P=1000mb,Th=970mVP=500mb, Th=970mV
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 19
~460V
~420V
08 September 2009A.Kashchuk INFN-Ferrara and PNPI-
St.Petersburg20
0102030405060708090
100110120130140150
0 5 10 15 20 25 30 35 40
Point number along straw (40cm, step 1cm)
Fe-
55 p
eak
po
siti
on
(m
V)
Mean=133.2StDev=1.25Ratio=0.94%
Good gas gain uniformity along straw
Good Fe-55 spectraand HV-plateau
At P=500mb (1500mb absolute)
1550V
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 21
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 22
The technique
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 23
Fe-55 creates the signal in only one straw: counts N1, N2 N1, N2 Cross-talk, if the signal appears in both straws:
Fe-55
N1N1 N2N2
ANDAND
AND/(N1+N2)AND/(N1+N2)
Electrical cross-talks (X-talks) between 2 straws below 10-3 for X-rays Fe-55
0500
1000150020002500300035004000
1100 1200 1300 1400
HV (V)
Fe-
55 c
ou
nt
(Hz)
#1 (Cu) #2 (Al) #1 w/o #2 w/o
0.0%
0.1%
1.0%
10.0%
100.0%
1100 1200 1300 1400
HV (V)
El.c
ross
-tal
ks (
%)
Cross-talks (%) w/o Next day
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 24
0.1%-level
AND
N1, N2
Does not dependconnected to groundor not (see w/o) the external layer
0
10
1000
1100 1200 1300 1400 1500 1600 1700
HV (V)
Fe-
55 c
ou
nt
(Hz)
#1 (Cu) #2 (Al) AND#1 w/o #2 w/o AND w/o#1 next #2 next AND next
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 25
log10 scale
Above 1500V: Z-talks can reach 100%Electrical cross-talks are masked by Z-talks above 1500V
AND
N1, N2
Cross-talks in straw tube detectors by schematics
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 26
Common impedance (Z-talks)Common impedance (Z-talks)
ResonanceResonance
SolutionSolution
Electrical coupling (X-talks)Electrical coupling (X-talks)
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 27
Electrical cross-talks vs. threshold(HV=1450V)
y = -0,31x + 3,18
y = -0,18x + 3,18
-1-0,5
00,5
11,5
22,5
33,5
0 5 10 15 20 25
log
(AN
D)
Th (mV)
#1 HV=0 #2 HV=1450V at Th-scan
#1 HV=1450V #2 HV=0 at Th-scan
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 28
Fe-55 count 1500Hz (extrapolation)
Offset ch#2=959mV (CARIOCA_hot 13mV/fC)
Offset ch#1=963mV(CARIOCA_hot 11mV/fC)
Note: offset subtracted Th=1fC
log(1500)=3.17
Z-talks vs. thresholdThe lines become more and more horizontal with increasing HV
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 29
Fe-55 count 1500Hz (extrapolation)
Offset ch#2=957mV (CARIOCA_hot 13mV/fC)
Offset ch#1=965mV(CARIOCA_hot 11mV/fC)
Note: offset subtracted Th=4fC at same gas gain will correspond to 12 p.e.(12% inefficiency)
log(1500)=3.17
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 30
?
Count multiplication seen by scope HV=1750V: Direct signal from CARIOCA – blue; First hit - red
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 31
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 32
Fe-55 Cu #003
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 33
~600V
150-200V
Dis
char
ge
lim
it ~
1850
VD
isch
arg
e li
mit
~18
50V
‘pro’=dead time prolongation(1-st hit counting)
HVop>1550VRaether limitRaether limit
~2×10~2×107 7 ee
Fe-55 Al #004
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 34
~600V
150-200V
Dis
char
ge
lim
it ~
1820
VD
isch
arg
e li
mit
~18
20V
‘pro’=dead time prolongation(1-st hit counting)
HVop~1550V Raether limitRaether limit~2×10~2×107 7 ee
Inductance in common ground creates ringing Inductance in common ground creates ringing on the FEE-input resulting multiple count on outputon the FEE-input resulting multiple count on output
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 35
Z-talksZ-talks
CountCountratioratio
Fe-55
Z-talksZ-talks
Z-talksZ-talks
Fe-55
Str
eam
ers
Str
eam
ers
tt
Streamers also create multiple pulses Streamers also create multiple pulses but longerbut longer
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 36
HV=1820V: Direct signal from CARIOCA – blue; First hit - red
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 37
Sc. counter
Straw 1
Straw 2
Note:Count collected during ~17mn/point3000 events on plateauper 24 hours for tracking
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 38
HVop>1550V
MIP~400V
Z-talks region
Z-talks can and must be
suppressed
Missing
11 22
33
Note:11 --Missing ~200Vdue tolower primaryIonization22 --HV-plateaufor MIPcontinue up todischarge limit33 --Z-talks region
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 39
Z-talks
Hvop>1550V
08 September 2009 A.Kashchuk INFN-Ferrara and PNPI-St.Petersburg 40