1. Results achieved so far to improve the RPC rate capability
G.Aielli for the ATLAS RPC group

2. Improvement of detector rate capability
Detector rate capability limited by voltage drop on resistive electrodes. Strategies to improve rate capability:
𝑉 𝑔𝑎𝑠 = 𝑉 𝐴 −𝑅∙𝐼= 𝑉 𝐴 −𝜌∙𝑑∙Φ∙𝑄( 𝑉 𝑔𝑎𝑠 )
Reduce resistivity
Allows to work at higher rates and depends on temperature, relative humidity of both gas and environment. Does not solve the problem of the ageing (if any).
Reduce average charge/avalanche. Grants at the same time an higher rate capability at constant current.
Reduce electrode thickness
A reduction of the electrode thickness from 1.8 mm to 1.2 mm has been recently achieved (BME chambers – bulit in 2013). But the main focus of the past R&D was on reduction of the average charge per count.

3. Development of a new fast charge amplifier.
A custom charge-to-voltage amplifier in BJT technology was purposely developed for this application.
Importante feactures are : extremely good signal/ration , radiation hardness and possibility to match low impedence trasmission line
Example of Input pulse (above) and relative output pulse (below)
Properties of the preamplifier
Working principle
Voltage supply
3-5 Volt
Sensitivity
2-4 mV/fC
Noise (up to 20 pF input capacitance)
1500 e- RMS
Input impedance
Ohm
B.W.
MHz
Power consumption
10 mW/ch
Rise time input
300 – 600 ps
Radiation hardness
1 Mrad, 1013 n cm-2
Concept schematics of the amplifier
Presentation by R. Cardarelli (INFN Roma Tor Vergata), New diamond detector structure and related front-end electronics for sub-nanosecond TOF application, at 13th Topical Seminar on Innovative Particle and Radiation Detectors, Siena 2013

4. Improvement of detector rate capability
Reduction on average charge per count by use of a new fast charge amplifier in Silicon BJT technology. From 20 to 3 pC/count for MIPS
20 pc/count
3 pc/count
The introduction of the new preamplifier permits a shift of the efficiency curve for a ATLAS like RPC (2 mm gas gap) at lower voltage – lower charge per count.

5. Improvement of detector rate capability
Test beam result at the Gamma Irradiation Facility (CERN) on an homogeneously irradiated detector.
ATLAS like 2 mm gas gap 20 x 20 cm^2 size with new FE
The total charge per count lowers from 30 to 4 pc/count (average for the GIF photon induced counts
New working point  full efficiency at a rate of 7 kHz/cm2.
The plateau shift is fully compatible with the Ohmic drop on resistive electrode.
R. Cardarelli, A fast electronics for RPC based precision tracking muon trigger at high luminosity LHC, Oral presentation at XI workshop on Resistive Plate Chamber and Related Detectors, LNF, 2012.

6. Improvement of detector rate capability
Efficiency vs Applied voltage for a 1+1 mm bigap RPC
Test carried out with a different detector layout: Result for a 1+1 mm bi-gap RPC operated with the new preamplifier.
Further improvement with respect to the 2 mm gas gap with the same electronics
Total charge per count ~2pc/count, to be compared to the ATLAS standard gap and FE of 30 pc/count
Full efficiency at a counting rate of 11 kHz/cm2
L. Paolozzi (INFN Roma Tor Vergata), Performance of a new generation RPCs for particle physics at colliders of the next generation, Poster at 13th Vienna conference on Instrumentation, Vienna, 2013.

7. Improvement of detector timing performance
Time distribution for a 1 mm gap RPC at low counting rate. Readout by NINO Front End.
Time distribution for a 1 mm gap RPC at a counting rate of 3 kHz/. Readout by new custom preamplifier. Raw resolution 7309 ps including the trigger scintillator jitter of 550 ps.
Time resolution in high rate environment after correction for trigger jitter:
𝛔 𝐭 =𝟒𝟖𝟎±𝟐𝟎 𝐩𝐬
The result obtained at high rate is compatible with the one obtained at lower rate with the same detector.
L. Han, Studies on fast timing and high precision tracking trigger based on Resistive Plate Chambers, Poster at 13th Vienna conference on Instrumentation.
L. Paolozzi, Performance of a new generation RPCs for particle physics at colliders of the next generation, Poster at 13th Vienna conference on Instrumentation.

8. Improvement on frontend preamplifier
Preliminary results and simulations for SiGe technology applied to the new preamplifier.
Silicon amplifier
SiGe amplifier
R. Santonico, Problems and opportunities for the RPCs of the next future, Oral presentation at XII workshop on Resistive Plate Chamber and Related Detectors.
Pulses recorded from a 500 micron diamond sensor irradiated by 241Am source.
Single stage amplifier for SiGe technology: sensitivity limited from scope noise.

9. Improvement on front-end preamplifier
From Cadence simulation of the full preamplifier in SiGe technology:
Simulated amplified pulse for a 3 fC input signal
Noise ≅ 200 electrons RMS

10. Summary and timeline of the preliminary R&D phase
2008 first prototype of a new FE scheme with a standard BJT applied to diamond detectors
2009 First prototype of a 20x20 cm^2 size bi-gap RPC with a gamma source
2010 first RPC ATLAS-like prototype (2 mm gas gap) 20 x 20 cm^2) equipped with the NEW FE realized on a dedicated discrete component PCB. Beam and GIF rate capability test
2011 first test of a Bi-gap small prototype( 20x20cm^2) at the GIF with the new FE
2012 first prototype of discrete component SiGe preamplifier based on the new FE concept

11. Expected R&D timeline Activity 2014/06 2014/09 2014/12 2015/03 2015/06
2015/09
2015/12
2016/03
2016/06
2016/09
2016/12
2017/03
2017/06
2017/09
2017/12
New Gas Search
New Gas GIF validation
SiGe chip FE development
Final SiGe chip FE Pre Production
New gas gap lab studies
Large size gap high rate validation
Module 0 production and beam test
Module 0 performance and Ageing test

12. Conclusions
Preliminary test on small RPC prototypes (20x20cm^2) with higher rate capability already quite good. Further tests needed to confirm and to optimize the performance
More R&D needed on realistic size prototypes (~1m^2)  define in a new layout and test the performance
More investigation on the thinner gas gap construction to fit the ATLAS need for BIS07/08
Ageing studies also need to be done