1. Performance of the HADES-TOF RPC wall in a Au-Au beam
Blanco
On behalf of HADES RPC Group
Sixth framework programme

2. Outlook HADES spectrometer RPCs in HADES
Intrinsic RPC performance in Au + Au 1.15 AGeV
- Time resolution, time tails and longitudinal spatial resolution
Calibration and PID plot
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

3. Large acceptance, high precision and rate capability
HADES spectrometer
The investigation of hadron properties inside nuclear matter at normal and high densities and temperatures is one of the main goals of current nuclear physics studies. Under these conditions, considerable modifications of basic hadron properties (masses, decay widths, etc.) are expected.
Large acceptance, high precision and rate capability
Shower
RPC
TOF
Magnet
MDC IV
MDC III
MDC II
RICH
MDC I
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

4. HADES spectrometer Located at: Darmstadt, Germany. www-hades.gsi.de
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

5. 8 m2 HADES spectrometer. RPC-TOF Located at: Darmstadt, Germany.
www-hades.gsi.de
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

6. loss probability below 20%
HADES spectrometer. RPC-TOF
Multi -
hit capability
hit -
loss probability below 20%
Time resolution
100 ps ( s
) or better
Rate capability
up to 1 kHz/cm 2
in some areas
Efficiency
above 95% for single hits
Area
~8/6 m2/sector
Fundamental option: shielded detectors, Cells
Independent hits in terms of timing  robust multihit performance
Cluster size ~ 1  efficient use of the electronics channels
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

7. Fully electrically shielded
The HADES RPC Cells
mm x 4 gaps
Minimum for good efficiency
2 mm aluminum and glass electrodes
Minimize amount of glass for maximum rate capability
Try to keep good mechanics
- Heat – tolerant materials
Fully electrically shielded
Aluminum
Spring-loaded pressure plate
Glass
HV & readout
in the center
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

8. Sector segmentation 3 Columns t1 32 Rows t2 2 layers
- 186 cells/sector distributed in 32 rows and 6 columns, 3 on top and 3 on bottom (2 layers)
cell in total
124 different cells with variable width, length and shape
Read out at both sides T = (t1 + t2)/2 X = t1 – t2
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

9. FEE and DAQ DAQ based on a 128 ch multihit TDC
[TNS 58 vol , 1745]
FEE based on Philips BGM1013
G = 35.5 dB, BW = 2 GHz, NF = 4.5dB
[TNS 57 vol , 2848]
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

11. First Au + Au test run in HADES
Intrinsic RPC performance. Au AGeV
First Au + Au test run in HADES
Multihit environment
<n> ~ 15
Multiplicity/sector
One Au + Au collision from HGeant
simulation package
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

12. Vprop/2 [(t1-t2)/2 – (t’1-t’2)/2] =
Intrinsic RPC performance. Analysis
Overlapped cells t1
t’1 t2
t’2
Time difference
T = (t1+t2)/2 – (t’1+t’2)/2
Time resolution
σ t= σ(T)/√2
Position difference
X =
Vprop/2 [(t1-t2)/2 – (t’1-t’2)/2] =
Vprop/2[X1-X2]
Longitudinal
position resolution
σ x= σ(X)/√2
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

13. Position and charge information used to correct time
Intrinsic RPC performance. Time resolution, corrections.
Position and charge information used to correct time 5
Corrected
< σ t> = 111 ps
< σ t> = 104 ps
No corrected
2.5
ΔT (ns)
-0.5 -5
1.5
X1 position (ns)
X1 position (ns)
Corrected
No corrected
< σ t> = 74 ps 1
0.5
0.5
ΔT (ns)
-0.5 -1
Q1 (A.U)
Q1 (A.U)
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

14. Intrinsic RPC performance. Time resolution
Requirement 100ps
Homogeneous time resolution < 100 ps
<σt> = 80 ps
σ t (ps)
Row number
σ t (ps)
Sector 2
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

15. All channels have a resolution well below 100 ps
Intrinsic RPC performance. Time resolution
81 ps
80 ps
79 ps
82 ps
78 ps
σ t (ps)
Row number S5 S4 S3 S2 S1 S6
< σ t Global> = 80 ps
All channels have a resolution well below 100 ps
< σ t>
Requirement 100ps
Out of a total of 1116 cell, 1114 are operative along with 2232 FEE
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

16. Intrinsic RPC performance. Time resolution, multihit
Multihit time resolution
All events
σ t (ps)
Sector 2
Row number
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

17. Intrinsic RPC performance. Time resolution, multihit
Multihit time resolution
Selection of a standard hit (hit in overlapped cells) + at least other valid hit in the same row
n+1 n
n-1
Row
Second hit in the same row
All events
σ t (ps)
Sector 2
Row number
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

18. Intrinsic RPC performance. Time resolution, multihit
Multihit time resolution
Selection of a standard hit (hit in overlapped cells) + at least other valid hit in a cell located beyond 4 rows
Second hit in the same row
All events
Second hit in  4th row
σ t (ps)
Sector 2
Row number
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

19. Intrinsic RPC performance. Time resolution, multihit
Multihit time resolution
Neighbor in the same row
Neighbor in the  4th row
Standard analysis
Au AGeV
σ t (ps)
Neighbor hit has no impact
Sector 2
Distance (rows) to the neighbor hit
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

20. Crosstalk probability
Intrinsic RPC performance. Crosstalk
Log scale !!
Crosstalk probability
Crosstalk to row
Sector 2
Row number
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

21. Intrinsic RPC performance. Crosstalk
Log scale !!
Crosstalk probability
Crosstalk to row
Sort range affecting only the nearest rows
Sector 2
Row number
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

22. Intrinsic RPC performance. Time resolution, Plow, Phigh, π+
<σt>=70 ps
Plow energy
<σt>= 50 ps
Phigh energy
<σt>= 64 ps
Beta
p * q (Mev/c)
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

23. Intrinsic RPC performance. Time tails
PRELIMINAR !!!
<T300>=0.04
Tails left
Tails right
T300
T700
<T700>=0.02
Tails left
Tails right
Symmetric left and right time tails.
σt (ps)
T700
Average for all sectors
<T300> = 3.6%
<T700> = 1.7%
Sector 2
Row number
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

24. Suppression of the tails in one side
Intrinsic RPC performance. Time tails, double layer advantages
Tail cancellation using redundant information (overlapping of cells) at a cost of efficiency
Suppression of the tails in one side
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

25. Intrinsic RPC performance. Spatial resolution
Homogeneous longitudinal position resolution < 10 mm σ
8.9 mm
σ x(mm)
Row number
σ x(mm)
Sector 2
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

26. Intrinsic RPC performance. Spatial resolution
8.7 mm
8.9 mm
9.1 mm
8.8 mm
8.1 mm
8.6 mm
< σ x>
σ x (mm) S5 S4 S3 S2 S1 S6
Row number
< σ x Global> = 8.9 mm
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

27. Raw <TOF> positioned around 8 ns
System RPC performance. Time calibration
Different offsets of individual cells must be corrected to create a isochronous surface. Protons are used since covers almost all the detector surface with high statistics.
Raw <TOF> positioned around 8 ns
S2 BC
Raw calibrated
TOF from RPC
TOFmeasured
<TOF> (ns)
Row number
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

28. *assuming all particles protons.
System RPC performance. Time calibration
Different offsets of individual cells must be corrected to create a isochronous surface. Protons are used since covers almost all the detector surface with high statistics.
Raw calibrated
TOF from RPC
TOFmeasured
ToF
Calibration
constant
Momentum (p) and
path length (L)
from tracking
Momentum
cut at 0.9 GeV
(avoid Mult.Scat)
TOFestimated* = L/v =
=L*mp/p
*assuming all particles protons.
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

29. TOFmeasured- TOFestimated for one RPC cell
System RPC performance. Time calibration
Different offsets of individual cells must be corrected to create a isochronous surface. Protons are used since covers almost all the detector surface with high statistics.
Peak due protons
Calibration
constant
Failed mass hypothesis
TOFmeasured- TOFestimated for one RPC cell
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

30. System RPC performance. Time calibration
Different offsets of individual cells must be corrected to create a isochronous surface. Protons are used since covers almost all the detector surface with high statistics.
<TOF> after calibration
S2 BC
Raw calibrated
TOF from RPC
TOFmeasured
ToF
Calibration
constant
Momentum (p) and
path length (L)
from R-K
Momentum
cut at 0.9 GeV
(avoid Mult.Scat)
TOF* = L/v =
=L*mp/p
*supposing all particles protons.
<TOF> (ns)
Row number
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

31. System RPC performance. PID
Beta
p * q (Mev/c)
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

32. Conclusions RPC-TOF fully integrated in the HADES spectrometer
and commissioned in Au + Au beam
Uniform time resolution <80> ps σ in a Au + Au environment, fullfilling the desing requirements
Ready for production beam time (April 2012).
Performance of the HADES-TOF RPC wall in a Au-Au beam A. Blanco RPC2012, 5-10 Feb 2012 Frascati

33. HADES RPC Group GSI D. Gonzalez W. Koenig LIP
A. Blanco N. Carolino O. Cunha
P. Fonte
L. Lopes
A. Mangiarotti A. Pereira C. Silva
C.C. Sousa
USC
D. Belver
P. Cabanelas
E. Castro J.A. Garzón G. Kornakov
M. Zapata
IFIC-Valencia
J. Diaz
A. Gil