The Tesla muon detector an update Marcello Piccolo St. Malo April 2002.

The Tesla muon detector The Tesla muon detector an update an update

Marcello PiccoloMarcello Piccolo

St. Malo April 2002St. Malo April 2002

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AgendaAgenda

A reminder of the TDRA reminder of the TDR Performances with single muonsPerformances with single muons Pions rejection ( single particles )Pions rejection ( single particles ) Punch through and decaysPunch through and decays Multijet environmentMultijet environment Some R&D results Some R&D results ConclusionsConclusions

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TDR reminder TDR reminder

The design is based on a long octagonal barrel.The design is based on a long octagonal barrel. The end caps are completely encompassed by The end caps are completely encompassed by

the barrel octagon.the barrel octagon. The barrel itself is longitudinally segmented in The barrel itself is longitudinally segmented in

three piecesthree pieces Transverse segmentation is 10 cm in the first Transverse segmentation is 10 cm in the first

100 cm of Fe absorber.100 cm of Fe absorber. In order to minimize the total detector area the In order to minimize the total detector area the

last 30% of the absorber does not house any last 30% of the absorber does not house any active detector: one last plane is foreseen after active detector: one last plane is foreseen after the absorber itself.the absorber itself.

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TDR reminderTDR reminder

Total Fe thickness 150 cm.Total Fe thickness 150 cm. (Some) Calorimetry capability built in.(Some) Calorimetry capability built in. Just a muon tagger... Limited momentum Just a muon tagger... Limited momentum

measurements capabilities.measurements capabilities. Threshold momentum around 5 GeV/c Threshold momentum around 5 GeV/c

with 4 Tesla B field.with 4 Tesla B field. Full efficiency ( > 95% ) above 8 GeV/cFull efficiency ( > 95% ) above 8 GeV/c Angular coverage complete Angular coverage complete minmin ~ 100 ~ 100

mr.mr.

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TDR reminderTDR reminder

8/11 planes8/11 planes planesplanes

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Single particle performancesSingle particle performances

Here is the Here is the response to response to muon (full) muon (full) and pions and pions (dashed)(dashed)

The overall The overall normalization normalization for the input for the input spectra differs spectra differs by a factor of by a factor of 5.5.

• 5 times 5 times more pions more pions than than muons.muons.

The vertical The vertical axis is axis is logaritmic.logaritmic.

The overal The overal rejection is rejection is better than better than 0.3%.0.3%.

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Single particle performances Single particle performances (cont.)(cont.)

In order to asses the In order to asses the overall goodness of overall goodness of the design, one should the design, one should see if the misidentified see if the misidentified pions come from pions come from punch through or from punch through or from decay,decay,

The optimized The optimized confguration obviously confguration obviously calls for a 50-50 mix of calls for a 50-50 mix of the two components. the two components.

Here is the truth table Here is the truth table for misidenfied pions for misidenfied pions propagating in the propagating in the calorimetric part of the calorimetric part of the Tesla detectorTesla detector

These results come These results come from a particles from a particles generated with a flat generated with a flat momentum and angle momentum and angle spectra.spectra.

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Moving to a jetty Moving to a jetty environmentenvironment

A first analysis has A first analysis has been performed on bb been performed on bb events in the barrel events in the barrel region.region.Here is the momentum Here is the momentum spectrum for particles spectrum for particles ending up in an angular ending up in an angular region between 0.81 region between 0.81 and 2.35 rad. (polar and 2.35 rad. (polar angle).angle).

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And comparing to muonsAnd comparing to muons

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Applying a naïve Applying a naïve identification algorithm identification algorithm

Require a Require a -stub crossing at least 8 -stub crossing at least 8 planes out of 11.planes out of 11.

The stub is defined by angular The stub is defined by angular consistency of the hits.consistency of the hits.

Matching a charged track in angle to the Matching a charged track in angle to the first hit of the stub results in the first hit of the stub results in the operational muon definition.operational muon definition.

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Here are the overall resultsHere are the overall results

The four spectra refer to:The four spectra refer to:

RED : generated primary RED : generated primary particlesparticlesGREEN: generated GREEN: generated BLUE : identified BLUE : identified YELL : misidentified YELL : misidentified

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Performances…good Performances…good enough?enough?

Identification efficiencies seem O.K.Identification efficiencies seem O.K. Pion rejection is 100 to 1.Pion rejection is 100 to 1. If anything, one would ask a better pion If anything, one would ask a better pion

rejection: an identified muon, in this rejection: an identified muon, in this class of events, has a 30% chance of class of events, has a 30% chance of being a misidentified pion.being a misidentified pion.

Why this deterioration with respect to Why this deterioration with respect to the single particle figure ?the single particle figure ?

Fake associations are the first bet.Fake associations are the first bet.

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Performances in bb jetsPerformances in bb jets

Let’s go to the Let’s go to the truth table truth table again, and again, and check the check the relation between relation between the hits in the the hits in the first layer and first layer and the associated the associated track (for track (for misidentified misidentified hadrons) .hadrons) .

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More in detail..More in detail..

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So, performances could be So, performances could be improvedimproved

Fake association do account for a sizeable Fake association do account for a sizeable part of fake muons….part of fake muons….• Better software might get rid of a good part of Better software might get rid of a good part of

them .them . Better extrapolation of charged tracks Better extrapolation of charged tracks

should be used : a first step can be the should be used : a first step can be the GEANE package.GEANE package.

As of now the matching is pretty crude: an As of now the matching is pretty crude: an angle cut both in polar and azimuthal angle cut both in polar and azimuthal view.view.

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Looking at figures…Looking at figures…

Assuming to be able to get rid of all the fake Assuming to be able to get rid of all the fake associations one would end up with the associations one would end up with the following background counts:following background counts: + 153 26+ 153 26 - 144 15- 144 15 + 44 33+ 44 33 - 50 35- 50 35 + 48 35+ 48 35 - 9 9 - 9 9

Comfortably close to the single particle Comfortably close to the single particle numbersnumbers

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Can the limiting rejection be Can the limiting rejection be reached ?reached ?

This is a detailed question that can be This is a detailed question that can be answered only with a complete simulation.answered only with a complete simulation.

I believe that some optimism is warranted: the I believe that some optimism is warranted: the achievable spatial resolution of RPC’ has not achievable spatial resolution of RPC’ has not been used in the preliminary analysis shown been used in the preliminary analysis shown before.before.

Proposed devices would allow spatial Proposed devices would allow spatial resolutions close to 0.5 cm. ( close to 1 mrad. resolutions close to 0.5 cm. ( close to 1 mrad. at the radius of the first layer): the matching I at the radius of the first layer): the matching I used in what has been reported was based on used in what has been reported was based on a 40 mrad . cut.a 40 mrad . cut.

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Last simulation topic: how Last simulation topic: how about a muon trigger ?about a muon trigger ?

Using a hit-Using a hit-stub to define stub to define a muon trigger a muon trigger one can one can evaluate which evaluate which kind of rate kind of rate and purity can and purity can be achieved.be achieved.

Here is a plot Here is a plot of the particle of the particle content of a 8 content of a 8 planes stub in planes stub in bb events.bb events.

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Detector R&DDetector R&D

Now let’s switch gear and move to a Now let’s switch gear and move to a different topic….different topic….

Up to now, in the simulation, detectors Up to now, in the simulation, detectors were a porridge of materials linked to a were a porridge of materials linked to a given spatial and/or energy resolution.given spatial and/or energy resolution.

We would like now to prove that the We would like now to prove that the figures we used are indeed achievable in a figures we used are indeed achievable in a sort of routine way, as the overall number sort of routine way, as the overall number of detectors calls for a mass production.of detectors calls for a mass production.

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Parameters to be shownParameters to be shown

The design of the The design of the detector calls for detector calls for efficient devices capable to yield space efficient devices capable to yield space resolution of 0.5-1.0 cm.resolution of 0.5-1.0 cm.

I will then show typical efficiency maps I will then show typical efficiency maps for a single gap RPC.for a single gap RPC.

Spatial resolution achievable on large Spatial resolution achievable on large detectors (2 mdetectors (2 m22) will also be shown.) will also be shown.

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Test set-upTest set-up

A cosmic test facility is operational in Frascati: it A cosmic test facility is operational in Frascati: it consists of 10 shelves to house RPC’ s up to 3x1 consists of 10 shelves to house RPC’ s up to 3x1 mm22 . .

Two more RPC on top and bottom provide trigger Two more RPC on top and bottom provide trigger and tracking.and tracking.

Electronics to read out the struck strips is the Electronics to read out the struck strips is the standard BaBar electronics.standard BaBar electronics.

Typical trigger rate is about 40 Hz; data are read Typical trigger rate is about 40 Hz; data are read into a DAQ pc essentially at the same rate.into a DAQ pc essentially at the same rate.

A slow monitoring stream to check currents and A slow monitoring stream to check currents and temperatures has been implemented too.temperatures has been implemented too.

Most of the work on this setup has to do with BaBar, Most of the work on this setup has to do with BaBar, it is, however easy to plan measurements relevant it is, however easy to plan measurements relevant to the muon detector for a linear collider apparatusto the muon detector for a linear collider apparatus

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A typical efficiency mapA typical efficiency map

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Spatial resolutionSpatial resolution

Typical resolution Typical resolution plot.plot.

The spike is well The spike is well represented by a represented by a single gaussian.single gaussian.

Ratio between Ratio between areas of the two areas of the two gaussians used in gaussians used in the fit is roughly the fit is roughly 10:1.10:1.

Overall resolution Overall resolution is is

0.66 cm0.66 cm

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R&D to do list R&D to do list

Local rate capability measurementLocal rate capability measurement• Assumed 10 hits/cmAssumed 10 hits/cm22 in streamer mode. in streamer mode.

Test performances with and without Test performances with and without linseed oil.linseed oil.

Test different mixtures to minimize Test different mixtures to minimize sensitivity to slow neutrons.sensitivity to slow neutrons.• Minimize Hydrogen content of gas mix.Minimize Hydrogen content of gas mix.

Test different working regimesTest different working regimes• Avalanche could allow an extra factor of 10 in Avalanche could allow an extra factor of 10 in

local ratelocal rate• A possible alternative as had-cal active device.A possible alternative as had-cal active device.

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Outlook and ConclusionsOutlook and Conclusions

The design philosophy for the muon The design philosophy for the muon detector doesn’t seem to show major flows. detector doesn’t seem to show major flows.

More detailed simulation needed to More detailed simulation needed to evaluate evaluate rejection rate in jetty events. rejection rate in jetty events.

R&D studies startedR&D studies started• Basic requirements for the proposed detectors Basic requirements for the proposed detectors

on hand.on hand.• More features of the proposed detectors to be More features of the proposed detectors to be

investigated …might even be used in the had-investigated …might even be used in the had-cal.cal.