stephen kahnparticle id software mice collaboration meeting page 1 particle id software steve kahn...

Stephen Kahn

Particle ID Software Mice Collaboration Meeting

Particle ID Software

Steve Kahn

Brookhaven National Lab

27 March 2003

Stephen Kahn


Particle Identification Systems

• Time-of-Flight system:

– Can separate from in the incoming beam by transit time between two upstream TOF stations.

– Can separate e from decay based on transit time.

• Cherenkov Detector Systems:

– Upstream system

• Supplied by University of Mississippi

– Downstream system

• Supplied by Université de Louvain.

• EM calorimeter:

– Downstream to separate electromagnetic energy (e, ) from .

Stephen Kahn


Glossary of Terms Used in MICE Software

• Simulation:– Tracking through cooling and detector channels.– Hits produced in active detectors contain the true track parameters.– Output file is called Sim.out

• Digitization:– A response to a track traversing a detector can be recorded.

• This recording is referred to as a digitization. It can be– ADC counts representing the pulse height in a phototube.– TDC counts representing a time measurement of the track

traversing the detector.

– These digitizations are not the true track variables. They represent how the detector sees the track.

– The digitization output file is called Dig.out

Stephen Kahn


Glossary, continued.• Reconstruction:

– Although the detector digitizations contain all the information that can be known about the, they are not directly realizable as kinematic variables.

– The reconstruction process translates the digits into kinematic variables as best it can.

• These reconstructed variables will differ from the original simulated measurements because of detector measurement errors.

– The output file of this process we call rec.out • The original true variables are carried along for comparison, however

they will not be available for the experiment.• Analysis:

– Plotting detector simulated data.– Comparing reconstructed variables to true variables.– Determining the particle ID (is this a muon?)– Calculating the emittance.

Stephen Kahn


TOF I Station

• TOF I is located after 1st diffuser where beam comes into hall.– This at –15 meters from center of cooling cells.– TOF I is 1212 cm2 in size.– TOF I is composed of two planes oriented in X and Y

respectively • Each plane is segmented into two slabs with phototubes

on each end.• Each slab is 1262.5 cm3.• Using Bicron BC-420 fast Scintillator.

– Use Hamamatsu R4998 Phototubes on each end.• 0.7 ns rise time, 160 ps transit time jitter

Stephen Kahn


TOF II AND TOF III Stations

• TOF II (TOF III) is located before (after) the upstream (downstream) measurement solenoid.– This is at –5.544 meters from the center of the cooling cells.– TOF II, III are 4040 cm2 in size.– TOF II, III are composed of a single Y oriented plane.

• The plane is segmented into 8 slabs.• Each slab is 4062.5 cm3.

– There is ~1 cm overlap at the edges of the slabs to allow cross-calibration.

• Bicron BC-404 Scintillator is used for these stations since it has a longer attenuation length than the BC-420 used in station I.

=1.7 meters.

Stephen Kahn


TOF II and III continued

• The choice of phototube to use for the TOF II and TOF III stations is complicated by the presence of fringing magnetic field from the measurement solenoids.– The field situation is shown in the following transparencies.– The fast phototube used for TOF I (R4998) does not

tolerate much magnetic field. The choices are• Shield the fast Hamamatsu R4998 phototubes.• Use the Hamamatsu R5505 fine mesh phototube which

can handle fields up to ~1 Tesla.

Stephen Kahn


Stephen Kahn


Time Resolution: trecon-ttrue

TOF 1: =35 ps TOF 2: =108 ps

TOF 3: =108 ps

Stephen Kahn


Transit Time from TOF1 to TOF11

~20 tracks consistent w/ electrons from mu decay

Stephen Kahn


Original Mississippi Downstream Cherenkov

• The original downstream Č system that was in the Dec ’02 version of the simulation was based on a 10010015 cm3 aerogel radiator segmented into an array of 1010 cm2 tiles, each with 2 PMT for light collection.– The geometry of this system

was implemented in Geant4.– There was a detector response

coded for the PMTs, but it does not appear to have a Č response.

• Geant, itself, can create and track Č photons.

Stephen Kahn


Upstream Cherenkov Detector

• The upstream Cherenkov detector will be based on the Mississippi design. It is likely to be simpler than the original.

• At this point it is not in the current MICE Geant package.

– It should be straight forward to modify the original code from Romulus Godang to put it in.

Stephen Kahn


Downstream Cherenkov System

• Developed by G. Grégoire of Université de Louvain.

• The radiator is aerogel with nrefraction=1.02 and covers 9090 cm2 and has a thickness of 10 cm.

• Light is reflected by 45º mirrors into 20 diameter Hamamatsu R3600-02 PMTs. (Super K kind).

– Large gain 3106 needed for low Č light yield in aerogel.

– 24 cm PMT photocathode radius.

Stephen Kahn


Spatial distributions

0

500

1000

1500

-300 -200 -100 0 100 200 300

X (mm)

N Muons

Electrons

0

500

1000

1500

-300 -200 -100 0 100 200 300

Y (mm)

N Muons

Electrons

Beam spot ~300 mm diam. ~ size of the radiator

Numerical aperture (f-number) = ~ 1.5

x

y

0

500

1000

-40 -20 0 20 40

Theta XZ (degrees)

Muons

Electrons

0

500

1000

-40 -20 0 20 40

Theta YZ (degrees)

Muons

Electrons

xz

yz

Divergence ~ 20° sin2

1f

Slide from Gh. Grégoire July 9, 02 Presentation

Stephen Kahn


Angular and energy distributions

0

200

400

600

800

1000

1200

1400

0 10 20 30 40

Theta (degrees)

N

Muons

Electrons

0

200

400

600

800

1000

1200

1400

1600

1800

0 100 200 300 400 500Total energy (MeV)

N

Muons

Electrons

Angle with respect to beam axis

Kinetic energy distribution

It is not obvious (to me) to separate e- on calorimetric principles at such low electron energies!

Electrons have very low energies ( E< m )

Slide from Gh. Grégoire July 9, 02 Presentation

Stephen Kahn


Current Status of the Downstream Č Geant Software

• A model of the Louvain Č detector has been coded.

– DetModel classes: CKOV2Tracker

• CKOVHit and CKOVSD slightly modified, but are common with Upstream Č

– Config classes: CKOV2TrackerGeom

– Interface classes: CKOV2HitBank

• Inherits from CKOVHitBank

– DetResp classes: CKOV2Digits

– Calib classes: CKOV2DigitParams

Stephen Kahn


Current Status of Č Software

• The CKOV2Digit does try to simulate what each of the 4 PMTs would see from the Č process.

– There is no signal for imaginary Č angles. µ’s and e’s will look different.

• This new downstream Č classes exists on my computer.

– They are not yet in CVS (Yagmur says that means they do not exist)

– They compile and link. They are being verified.

Stephen Kahn


Particle ID Package Status

Package Geometry Digitization Reconstruction Analysis

TOF √ √ √ ?

Orig Č √ √

Upstream Č

Downstream Č √ √

EM Cal √ √

stephen kahnparticle id software mice collaboration meeting page 1 particle id software steve kahn...

Documents

stations tof

upstream tof stations

mice software simulation

true track variables

detector digitizations

time measurement

detector channels

kinematic variables