ATLAS RPC phase-2 proposal

D.Boscherini for the ATLAS Coll. and S.Bianco for the CMS Coll. R&D RPC phase2 - Rome May 9th 2014 1

ATLAS RPC phase-2 proposalCompletion of the detector for the barrel muon trigger via the installation of new trigger stations in the inner layer of the spectrometer (currently equipped only with MDTs)

Increase the number of measurement stations from 2 3Increase the number of independent layers from 6 9

RPC0(BI)

RPC3

RPC2

RPC1


ATLAS RPC phase-2 proposalThe inner layer was already considered in the original project of the barrel trigger detector, but at that time the need for the 3rd station was not stringent and it was cancelled

Trigger performance improvements with the new RPC inner layer:- larger acceptance

The new chambers will substantially increase the trigger coverage by filling the acceptance holes due to the barrel toroid support

structures- increased selectivity

The larger lever arm and the improved spatial and time resolution of the new RPCs will allow to apply a sharper momentum cut- increased chamber redundancy and longevity

the new layer will increase the redundancy well above the current 3/4 low-pt majority. This will also allow to operate the middle chambers at lower voltage, decreasing the integrated charge, without loss in the

overall trigger efficiency


Barrel trigger coverageHigh-Pt trigger acceptance currently limited at ~72%due to non-instrumented regions in:- feet + elevators (partial recovery in LS1)- toroid (and ribs) in BM chambers of small sectors

Holes are not projective and 3/3 RPC chambers are required in the trigger with RPC BI chambers use 3/4 request

LVL1 barrel

1.00.750.4η=0.0


Barrel trigger coverage

Single muon MC studyfor different trigger options

Trigger requirement Acceptance wrt muon reconstruction, ηmuid<1.05

RPC1 && RPC2 && RPC3 72%

RPC0 && (RPC1||RPC2) && RPC3 82%

any 3 out of 4 chamber layers 88%(any 3 out of 4) || ( inner && outer) 96%

current trigger logic


Redundancy exploitationThe produced charge, responsible for the detector aging, can be reducedby decreasing the operating voltage(this is equivalent to work at lower rate and much lower current)The detector efficiency will consequently decrease

- the loss in efficiency is compensated by a less stringent requirement in low-pt trigger:

3/4 2/4 majority- the rejection power would be guaranteed by the additional RPC in the BI chambers

2/4

3/4

0

0.2

0.4

0.6

0.8

1

1.2

8500 9000 9500 10000

Standard voltage (V)

Effic

ienc

y


Requirements on the new RPCsAccording to Atlas requirements the qualification tests were done taking as reference luminosity L=1034 cm-2 s-1, assuming 10 years of running at max background rate of 100 Hz/cm2 (including a safety factor of 5 wrt simulation)

Expected max rate in new inner layer ~1 kHz/cm2:need to improve the long term RPC rate capability to sustain the LHC luminosity in phase-2

Limited space available for the installation in the inner layer: ~5cm

Reduced gas gain:- thinner gap 2 1 mm- thinner electrodes 1.8 1.2 mm - increased amplification in front-end electronics

Improved spatial and time resolution:- timing is improved by reducing the gap thickness- use ToT and charge centroid to improve spatial resolution

Reduced detector thickness- higher-quality mechanical structures


CMS RPC phase-2 proposalTwo types of upgrades proposed for the CMS RPC muon system:1. Aging and longevity: built in 2003 and

installed in 2007, must continue to operate without significant degradation degradation (<eff> = 95%, CS < 3, noise < 1 Hz/cm2) well beyond the design expectations of the LHC; in particular, with respect to a large integrated radiation dose and also a very long time period of operation.

2. Upgrade of high eta region: keep performance of trigger and low pT<20GeV threshold even at an increased luminosity• Background rejection and muon reconstruction• Costant trigger rate with PT < 20 GeV • HZZ*2m, 4m; Ht+t-mX; etc• NEW STATIONS RE3/1 and RE4/1

Technical Proposal in progress

due July 2014


RE3/1 & RE4/1

– 144 chambers (about 1.5-2.0 m2 area) for the inner (ring n.1) region of disks 3 and 4

– Rate: 1-2 kHz/cm2 • x5 limit tested for existing RPC chambers

– Integrated charge: 1-2 C/cm2 @ 3000fb-1

• Proposed to cover the very forward region (1.6< |h| <2.4)

Barrel muon system is covered with 8 layers of chambers (58 hits max) Endcap region is covered with 8 layers (28 hits max)High eta region is covered with 4 layers (24 hits max)


CMS RPC in muon reconstruction

• Recovery of efficiency

thanks to RPC tracking

During RUN1 the stability of the muon system has been assured thanks to the 2 independent trigger/detector systems.A major CSC faults occurred in the 2012 (7 chambers off in ring1) but thanks to the RPC (ring 2) we were able to recover part of the inefficiency even in this region. With a full coverage the system will be stable in case of any trouble.


CMS RPC in muon trigger• All 3 muon triggers (RPC,

DT, CSC) contribute to the stability of the muon trigger efficiency and to the control of the rate.

• From the 2016 all the muon data will be used in a unique algorithm in order to have more robust system in the view of the lumi/background increment foreseen.


Joint ATLAS-CMS phase 2 R&DCMS-specific

• Operation at 1-2kHz/cm2, 1-2 C/cm2 @3000fb-1

• Improved time resolution (10-100)ps– Background reduction– Secondary vertices

• iRPC– Large area, improved, multigap RPC• with HPL / glass electrodes


1. Electrode


2. Chamber prototypes


3. FEE


4. The “ecological” gas mixtures issue

The European Community has prohibited the production and use of gas mixtures with Global Warming Power > 150 (GWP(CO2) = 1)

This is valid mainly for industrial (refrigerator plants) applications

Scientific laboratories would be excluded

CERN could require to stick to these rules anyhow

C2H2F4 is the main component of the present RPC gas mixture:

GWP(C2H2F4) = 1430, GWP(SF6) = 23900, GWP(iC2H10) = 3.3

C2H2F4 and SF6 Crucial to ensure a stable working point in avalanche

Similar problem for CF4 (GWP = 5800) used in GEMs for time resolution

On the physical and chemical properties of this components we:

Designed FE electronics and chambers

Did all performance, ageing and calibration tests


Test molecules similar to C2H2F4 but with lower GWP

C3H2F4 – tetrafluoropropene (GWP=4)

Should replace C2H2F4 as automotive air-conditioning refrigerant

C2H4F2 – difluoroethane (GWP=120)

Also studied to replace C2H2F4 as a refrigerant

C2HF3Cl2 (GWP=93), others…

Plan to measure all the detector response parameter (time, charge spectrum, streamer separation, noise, efficiency, possibly drift velocity) HUGE PARAMETER SPACE, NEED TO DIVIDE MEASUREMENTS BETWEEN FACILITIES

Test at the GIF++ will follow on a short list of candidates to measure the performance in a realistic environment Rate capability, performance under stress, HF yield already being setup at GIF New ageing tests (to be performed also at GIF++)

4. The “ecological” gas mixtures issue: Plan


TFP has a strong effect both in quenching and in keeping the charge at low levelmixtures are promising even for avalanche working mode with an appropriate FE Electronics and a dedicated chamber layout

First results on new gas mixtures for RPCsGas mixtures tested:Ar/C4H10/TP 83-3-15with increasing % of SF6

Preliminary

A long R&D program is needed to analyze all the proposed gases and variants

First with cosmics, then at GIF Single-gap ATLAS prototype, read on the oscilloscope, average charge vs. efficiency

Ref: B.Liberti et al, RPC2014 Beijing


ATLAS Tor Vergata

Spazio per foto e qualche riga sul laboratorio di Tor Vergata


CMS Frascati

Spazio per foto e qualche riga sul laboratorio di Frascati


The Quest for Ecogascharacterizing interaction of candidate ecogases with RPC materials

• Chemistry• Reactivity• Outgassing• Production of HF ?• Production of other contaminants?– Ex.: CF3I under discharge releases CF3 strong acid

and corrosive• Before and after irradiation


Setup and refs for materials studies• Op4cal sensors for RPC gas• –  M.Caponero et al., Use of fiber op4c technology for rela4ve humidity monitoring in RPC

detectors JINST 8 (2013) T03003• –  S.Grassini et al., Gas monitoring in RPC by means of non- invasive plasma- coated POF sensors ‐ ‐

JINST 7 (2012) P12006• –  Patent deposit ZEOSENSORS (n. RM2011A000621 24/11/2011)• •  Gas mixtures for RPC• –  S.Colafranceschi et al., A study of gas contaminants and interac4on with materials in RPC closed

loop systems JINST 8 (2013) T03008• –  S.Colafranceschi et al., Performance of the Gas Gain Monitoring system of the CMS RPC muon

detector and effec4ve working point fine tuning INST 7 (2012) P12004• –  L.Benussi et al., A New approach in modeling the response of RPC detectors Nucl.Instrum.Meth.

A661 (2012) S182- S185‐• –  L.Benussi et al, Study of gas purifiers for the CMS RPC detector Nucl.Instrum.Meth. A661 (2012)

S241- S244‐• •  Materials for GEM• –  G.Saviano et al., A study of film and foil materials for the GEM detector proposed for the CMS

muon system upgrade accepted by JINST (2014)


5. Irradiation tests


Single Event Effects study on the FE boards of the

improved RPC (2015-2017)• Motivations: study of radiation transient effects on the

FE electronics of the iRPC

• Study : cross section measurement of the transient fenomena induced by neutrons on the open input FE boards. We plan to use the following facilities: the Triga Mark II reactor in Pavia and the Louvain cyclotron. The first one covers a energy range till 18MeV which can be extended till 50MeV by the second one.

• Setup : a measurement station has been already assembled and used for previous tests. The station has been instrumented with : VME crate, LVoltage PS , VME scalers, NIM crate and NIM modules, PC.

• Additional costs to be addressed:

– irradiation and targets for flux measurement at Triga Mark II 4kEuro

– irradiation and transport costs for Louvain 7kEuro


Financial Requests (2015-2017)

• Qui table


spares


HPL: R&D relativo alla produzione di lastre di HPL a bassa resistività. Obiettivo è il raggiungimento di un valore di resistività inferiore di un ordine di grandezza rispetto a quello attualmente utilizzato (1÷6 x 1010 Ohm cm). Questo R&D è di interese comune ATLAS-CMS ma sarà seguito da CMS che ha studiato e contribuito allo sviluppo della produzione di HPL per RE4 con una nuova ditta di laminati (Puricelli) dopo la chiusura della ditta Panpla che aveva prodotto tutto l’ HPL per gli RPC degli esperimenti a LHC. La misura di resitività sarà fatta da CMS mentre il test della long term conductivity da ATLAS

Tot 35HPL 20Transportation 5Resistivity Meas 10

• Acquisto di un batch di HPL (1 batch= 80 lastre da 1.6 m x 3.2 ;) . Questo quantitativo è sufficiente per un certo numero di prototipi da 1mq per entrambi gli esperimenti e per circa 5 prototipi0 (fulls size) per ogni esperimento : 8 kEuro

• Sperimentazione bassa resistività presso la ditta Puricelli : 12 kEuro (basato su circa 50 test )

• Misure di resistività: costruzione di uno strumento portatile per la misura di resistività (alimentatore,adc,elettrovalvole, consumables) 7 keuro

• Test di long term conductivity sull’HPL : 3 keuto• Trasporti: le lastre saranno tagliate presso una ditta milanese e inviate alla GT per la

costruzione dei prototipi: 5 keuro

ATLAS RPC phase-2 proposal

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