[PPT] - Implementation and performance analyses of the aerogel Cherenkov PowerPoint Presentation

SLIDE 1

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Implementation and performance analyses of the aerogel Cherenkov counter for the Kaos spectrometer

Dr. Luka Debenjak

University of Ljubljana & Institute for nuclear physics, Mainz, Germany

April 5, 2013

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 2

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview 1

Introduction A1 experimental hall The KAOS spectrometer Scintillating fiber detector prototype

2

Aerogel Cherenkov counter Threshold Cherenkov counters The detector design

3

Simulations in SLitrani

4

Data analysis and results Calibration Test with cosmic rays Test with protons and positrons Test with protons and pions Test with kaons

5

Overview

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 3

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

With the upgrade of the electron accelerator MAMI at the Institute for nuclear physics in Mainz, Germany, the investigation of strangeness physics is possible: study of YN and YY interactions (Emax = 1.6 GeV).

Invariant Energy W (GeV)

1 1.2 1.4 1.6 1.8 2 2.2

2

(GeV/c)

2

Four-Momentum Transfer Q

0.5 1 1.5 2 2.5

MAMI-B MAMI-C N π N η Λ K Σ K N ρ N ω

E98-108 E93-018 E94-107 E05-115

Q2 = −qµqµ W = √s In electro-production of strangeness a proton/neutron is replaced by a hyperon. e + p − → e′ + K + + Λ

e e’

x y z

γ* θe scattering plane

K

+

Λ p θK

+

θΛ

reaction plane

φ

Quark-level process of kaon electro-production inside nucleus:

γ s u u d s u d u

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 4

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview A1 experimental hall

The A1 three spectrometer facility at MAMI: The spectrometers are labeled as A (red), B (blue) and C (green) with KAOS spectrometer in the middle (violet). Two additional magnetic dipoles are installed upstream of the target to compensate the

deflection. This enables measurements to be

performed at 0◦ kaon scattering angle.

Beam line Electrons Hadrons Pre-target beam chicane

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 5

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview The KAOS spectrometer

Detection of kaons is effective only in KAOS (short trajectory length & large momentum):

Kaon momentum (MeV/c) 200 300 400 500 600 700 800 900 1000 1100 1200 Kaon survival probability 0.1 0.2 0.3 0.4 0.5

C B A Kaos

Electron arm Collimator Magnetic dipole MWPCs ToF walls Hydraulic cylinders

Configuration single dipole

Max. momentum

2100 MeV/c Momentum acceptance (∆p/p) 50 % Solid angle acceptance 10.4 msrad Momentum resolution (δp/p) 10−3 Length of central trajectory 5.3 m

detector package: Hadron arm: multi-wire proportional chambers, scintillator walls and aerogel Cherenkov counter Electron arm: scintillating fibers

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 6

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Scintillating fiber detector prototype

Electron trajectories are measured by two planes of scintillating fibers:

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 7

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Scintillating fiber detector prototype

One bundle of scintillating fibers: One of the issues: NA = sin α = 0.71 Simulations done in Litrani. Relative number of detected photons with illuminated fiber corresponding to MaPMT ch.

Nr. 16 (experiment vs. simulation):
L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 8

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Threshold Cherenkov counters

The separation of rare kaons from the abundant pions requires the use of a Cherenkov detector.

0.2 0.4 0.6 0.8 1 500 1000 1500 2000 2500 3000 N/Nmax Particle momentum [MeV/c] kaons pions

Condition for Cherenkov radiation: vparticle > c0/n cos θC =

1 βn(ω) = c0 vn(ω)

n = 1.055 ⇒ pK+

th

≈ 1470 MeV/c pπ+

th

≈ 415 MeV/c radiator: silica aerogel

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 9

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview The detector design

M3 screw hole mm φ = 1 thin wire hole side bar aerogel aerogel mm φ = 1 side bar knot

20 40 60 80 100 200 300 400 500 600 700 800 R [%] wavelength [nm] aluminised mylar foil mylar foil mirror

270 aerogel tiles: Novosibirsk (Boreskov Inst. Catalysis/Budker Inst. Nucl. Phys.)- d = 2 cm + Matsushita Electric Works Ltd. aerogel - d =1 cm 12 Hamamatsu 127 mm (5”) PMTs: 10 x R1250 + 2 x SBA R877-100: QEmax = 35% 5 L Labsphere Spectralect relectance coating; relectivity: 95-98% from 300 to 1200 nm Aluminized mylar foil 6 segments

wavelength [nm] quantum efficiency [%]

H = 45 cm W = 150 cm f= 35

200 250 300 350 400 450 500 550 600 650 700

50 45 40 35 30 25 20 15 10 5

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 10

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview The detector design

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 11

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Simulated total number of photo-electrons vs. aerogel thickness:

2 4 6 8 10 12 1 2 3 4 5 6 7 8 9

Npe d [cm]

SBA R877-100 R1250

Simulated distribution of p.e. for positrons and pions at 720 MeV/c momentum:

pions

/ ndf

2

χ 35.73 / 14 p0 45.2 ± 2037 p1 0.053 ± 4.272 pe

N 5 10 15 20 25 30 Counts 50 100 150 200 250 300 350 400 pions

/ ndf

2

χ 35.73 / 14 p0 45.2 ± 2037 p1 0.053 ± 4.272

positrons

/ ndf

2

χ 54.87 / 18 p0 44.8 ± 2011 p1 0.071 ± 6.759

positrons

/ ndf

2

χ 54.87 / 18 p0 44.8 ± 2011 p1 0.071 ± 6.759 +

e

+

π p = 720 MeV/c, d = 3 cm

Different types of diffusive box in a single segment: Number of p.e. at different angles between the mirrors:

2 4 6 8 10 12 0.25 0.5 0.75 1

Npe x/a mylar foil white reflectance coating

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 12

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Spectrum of photons reaching the photocathode surface.

[nm] λ 250 300 350 400 450 500 550 600 650 700 Counts 2000 4000 6000 8000 10000 12000 14000

Generated wavelength for Čerenkov photons Entries 33491 Mean 465

[nm] λ 250 300 350 400 450 500 550 600 650 700 Counts 100 200 300 400 500 600 700 800

Entries 33491 Mean 465 nm

Wavelength of photons seen

Transitions, reflections and absorptions of photons inside AC:

Matsushita BIC/BNP Air Sodocal Cathode Matsushita BIC/BNP Air Sodocal Cathode

50 100 150 200 250

3

10 × Transition from material to material

Matsushita BIC/BNP Air Sodocal Cathode Matsushita BIC/BNP Air Sodocal Cathode

5000 20000 25000 30000 35000 Reflection inside material by material 10000 15000

Matsushita aerogel BIC/BNP aerogel Air Sodocal Cathode Wrap PM Reflective foil White coating

20 40 60 80 100 120

3

10 ×

Absorption by wrapping when coming from material Wrap PM Reflective foil White coating Matsushita aerogel BIC/BNP aerogel Air Sodocal Cathode

100 200 300 400 500 600 700

3

10 ×

Reflection by wrapping when coming from material

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 13

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Calibration

Example of analog signals from R1250 PMT (left) and R877-100 PMT (right): Example of a raw ADC histogram:

Mean 364.1 RMS 36.3 ± 437.7 Integral 3.067e+06 / ndf

2

χ 1150 / 1044 p0 12.6 ± 486.4 p1 1.4 ± 251 p2 1.64 ±

58.41

p3 8.49e-08 ±

8.11e-07

p4 0.000209 ± 0.002736 p5 0.165 ±

3.608

p6 41.9 ± 2225

TOP ADC 0 [cnts] 200 400 600 800 10001200 Counts

3

10

4

10

5

10

Mean 364.1 RMS 36.3 ± 437.7 Integral 3.067e+06 / ndf

2

χ 1150 / 1044 p0 12.6 ± 486.4 p1 1.4 ± 251 p2 1.64 ±

58.41

p3 8.49e-08 ±

8.11e-07

p4 0.000209 ± 0.002736 p5 0.165 ±

3.608

p6 41.9 ± 2225 KAOS/Cerenkov/TOP/Raw 0

1 p.e. peak matched in all PMTs & pedestal @ channel #0 ADCi =ADCtop

i

+ADCbot

i

Mean 1007 RMS 2.808 ± 689.7 Integral 3.017e+04 / ndf

2

χ 1001 / 167 Constant 1.5 ± 152.1 Mean 7.2 ± 1210 Sigma 8.8 ± 599.4

ADC 0 [cnts] 500 1000 1500 2000 2500 3000 Counts

2

10

3

10

Mean 1007 RMS 2.808 ± 689.7 Integral 3.017e+04 / ndf

2

χ 1001 / 167 Constant 1.5 ± 152.1 Mean 7.2 ± 1210 Sigma 8.8 ± 599.4 Segment 0 Mean 857 RMS 3.62 ± 700.4 Integral 1.872e+04 / ndf

2

χ 720.1 / 137 Constant 1.45 ± 95.65 Mean 5.8 ± 1289 Sigma 7.2 ± 413.8

ADC 1 [cnts] 500 1000 1500 2000 2500 3000 Counts 1 10

2

10

3

10

Mean 857 RMS 3.62 ± 700.4 Integral 1.872e+04 / ndf

2

χ 720.1 / 137 Constant 1.45 ± 95.65 Mean 5.8 ± 1289 Sigma 7.2 ± 413.8 Segment 1 Mean 887.9 RMS 3.978 ± 753.3 Integral 1.793e+04 / ndf

2

χ 651.4 / 157 Constant 1.23 ± 85.94 Mean 7.8 ± 1418 Sigma 7.3 ± 446.8

ADC 2 [cnts] 500 1000 1500 2000 2500 3000 Counts 1 10

2

10

3

10

Mean 887.9 RMS 3.978 ± 753.3 Integral 1.793e+04 / ndf

2

χ 651.4 / 157 Constant 1.23 ± 85.94 Mean 7.8 ± 1418 Sigma 7.3 ± 446.8 Segment 2 Mean 1043 RMS 4.902 ± 738.6 Integral 1.135e+04 / ndf

2

χ 536.6 / 107 Constant 1.38 ± 77.43 Mean 5.6 ± 1491 Sigma 6.4 ± 329.8

ADC 3 [cnts] 500 1000 1500 2000 2500 3000 Counts 10

2

10

3

10

Mean 1043 RMS 4.902 ± 738.6 Integral 1.135e+04 / ndf

2

χ 536.6 / 107 Constant 1.38 ± 77.43 Mean 5.6 ± 1491 Sigma 6.4 ± 329.8 Segment 3 Mean 1053 RMS 5.676 ± 752.2 Integral 8780 / ndf

2

χ 572.8 / 177 Constant 0.88 ± 49.14 Mean 7.3 ± 1463 Sigma 6.8 ± 447.3

ADC 4 [cnts] 500 1000 1500 2000 2500 3000 Counts 1 10

2

10

3

10

Mean 1053 RMS 5.676 ± 752.2 Integral 8780 / ndf

2

χ 572.8 / 177 Constant 0.88 ± 49.14 Mean 7.3 ± 1463 Sigma 6.8 ± 447.3 Segment 4 Mean 1039 RMS 5.791 ± 631.8 Integral 5952 / ndf

2

χ 213.3 / 117 Constant 1.3 ± 56.1 Mean 4.9 ± 1310 Sigma 5.3 ± 274.3

ADC 5 [cnts] 500 1000 1500 2000 2500 3000 Counts 1 10

2

10

Mean 1039 RMS 5.791 ± 631.8 Integral 5952 / ndf

2

χ 213.3 / 117 Constant 1.3 ± 56.1 Mean 4.9 ± 1310 Sigma 5.3 ± 274.3 Segment 5

ADCi = (rawADCi−pedestali)∗gaini

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 14

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Test with cosmic rays

A preliminary efficiency test of the Cherenkov counter was performed with cosmic rays. Detector placed between ToF walls in KAOS. Trigger: any G & any H

G AC H

ADC SUM [Nr. photo-electrons]

10 20 30 40 50

Counts

1 10

2

10

3

10

Efficiency: eff = Nr. of events above ADC thr.

Nr. of all events

cut condition [Nr. photo-electrons] 0.5 1 1.5 2 2.5 3 3.5 4 Eff [%] 10 20 30 40 50 60 70 80 90 100

ADC SUM ADC SUM w/o segment 0 and dE/dx cut β ADC SUM w/o segment 0 and w/

β 0.2 0.4 0.6 0.8 1 1.2 1.4 Counts 200 400 600 800 1000 1200 1400 H [MeV/cm]

TOF

dE/dx 1 2 3 4 5 6 7 8 9 10 G [MeV/cm]

TOF

dE/dx 1 2 3 4 5 6 7 8 9 10

200 400 600 800 1000 1200 1400

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 15

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Test with protons and positrons

ADC SUM [Nr. photo-electrons] 2.5 5 7.5 10 12.5 15 17.5 Counts 50 100 150 200 250

positrons protons

Probability for p producing Cherenkov photons = 0 (δ-electrons, scint. in the coating etc. ?)

set-up KAOS & SpekC beam-current 1.5 µA target 9Be 22.4 mg/cm2 KAOS trigger G ⊕ H ⊕tagger KAOS central mom. 900 MeV/c aerogel thickness 2 cm (Novosibirsk)

Coincidence time spectrum between KAOS and SpekC (detection cut condition: 1.5 p.e.):

[ns]

CH

T

40
20

20 40 60 Counts 500 1000 1500 2000 2500 3000

above threshold below threshold

)

µ

(p, )

(p,e

)

π

(p,

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 16

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Test with protons and pions

Like in previous test protons contribute mostly to the pedestal, but also to the

ne-photo-electron peak:

ADC SUM [Nr. photo-electrons] 2.5 5 7.5 10 12.5 15 17.5 Counts

2

10

3

10

4

10

5

10 pions protons set-up KAOS & SpekB beam-current 300 nA target lH2 KAOS trigger tracking G ⊕ H KAOS central mom. 720 MeV/c, 460 MeV/c aerogel thickness 2 cm (Novosibirsk) + 1 cm (Matsushita)

β with events below (left) and above (right) detection cut condition: 1.5 p.e.:

Below detection threshold

0.0 0.5 1.0 1.5 1000 2000 3000 4000 5000 Counts βTOF

Above detection threshold

0.0 0.5 1.0 1.5 100 200 300 400 500 Counts βTOF

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 17

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Test with kaons

Identification of kaons is more difficult comapred to protons and pions:

200 300 400 500 600 700 5 10 15 200 300 400 500 600 700 5 10 15

momentum MeVc timeofflight ns

1 10 100

Kaons are identified by dE/dx, TOF and information from Cherenkov counter. The mass in the hadron arm:

500 1000 100 200 300 400 500

Counts mass [MeV/c 2]

m = p

1

β2 − 1

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 18

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview Test with kaons

Missing-mass spectrum in the p( e, e′K +)Λ reaction with random coincidences (yellow)

subtraction. A clear peak is seen at

Mx ≈ 1115 MeV/c2.

]

2

Missing mass [MeV/c

1060 1080 1100 1120 1140 1160 1180 1200 1220 1240

Counts 20 40 60 80 100 120 ]

2

Missing mass [MeV/c

1060 1080 1100 1120 1140 1160 1180 1200 1220 1240

Counts 20 40 60 80 100 120

d5σ dΩ5∗ = Γv d2σv dΩ∗

K

d2σv dΩ∗

K =

N−NBG

t Ldt
Ω Γv(Q2,W )A(Ω)d5Ω∗

∆Ω5∗ = ∆Ee′∆Ωe′∆Ω∗

K

Q2 = 0.05 (GeV/c)2, ǫ = 0.4, W = 1726 MeV, φ = 40◦ First preliminary physics results from this measurement:

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

1
0.5

0.5 1 dσv/dΩK * [µb/sr] cos θK * MAMI K-Maid original K-Maid reduced Saclay-Lyon Regge-plus-resonance

e e’

x y z

γ* θe scattering plane

K

+

Λ p θK

+

θΛ

reaction plane φ

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 19

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Overview

For effective π+/K + separation in kaon electro-production experiments I have designed, constructed and calibrated a threshold Cherenkov counter and mounted it onto KAOS spectrometer in A1 facility at MAMI. A detailed simulation of optical processes and performance at various geometries have been performed using SLitrani. A series of in-beam and cosmics tests have been performed. By proper K + and Λ missing-mass identification the cross-section has been measured. I wish continue with my carrier in experimental particle physics at higher energies. In current shut-down at CERN I see perfect opportunity for such migration from mid to high-energy physics, where I can take part with detector and hardware upgrades.

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 20

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Backup: Λ decay

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 21

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Backup: Silica aerogel optical properties

Spectrophotometer:

50/50 mirror splitter mirror mirror monochromator lamp PMT sample

Transm ittance [%] 10 20 30 40 50 60 70 80 90 100 10 20 30 40 50 60 70 80 90 100 wavelength [nm ] 200 300 400 500 600 700 800 BIC/BINP (d = 2 cm ) Matsushita aerogel (d = 1 cm )

T(λ) = exp(−d/Λabs − d/Λsc) ⇒ T(λ > 350 nm) = A exp(Cd/λ4)

Λabs = −d/ ln A, Λsc = λ4/C

Hunt parameters Novosibirsk aerogel Matsushita aerogel A 0.828 ± 0.001 0.8719 ± 0.0003 C (905 ± 4) × 10−5 µm4/cm (1783 ± 4) × 10−5 µm4/cm

2 4 6 8 10 12 200 300 400 500 600 700 800

Λabs [cm] wavelength [nm]

Matsushita aerogel BIC/BINP aerogel

5 10 15 20 25 30 35 40 45 50 200 300 400 500 600 700 800

Λsc [cm] wavelength [nm]

Matsushita aerogel BIC/BINP aerogel

Hunt parameters before baking after baking A 0.815 ± 0.001 0.8393 ± 0.0008 C (1006 ± 4) × 10−5 µm4/cm (842 ± 4) × 10−5 µm4/cm

2 4 6 8 10 12 200 300 400 500 600 700 800

Λabs [cm] wavelength [nm]

after baking before baking

5 10 15 20 25 30 35 40 45 50 200 300 400 500 600 700 800

Λsc [cm] wavelength [nm]

after baking before baking

Λabs remains constant above ≈ 300 nm. Λsc at λ > 350 nm is described by the λ4 dependence (Rayleigh scattering).

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 22

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Backup: Kaos Logic

G Top (0-8) G Bottom (0-8) Analog Delay Sum & Split Card Digital Delay TDC ADC VUPROM FPGA TRIGGER LOGIC 8 Paddles 8x 8x 8x 8x 8x 8x 8x 8x 8x 16x 16x

CFD sum CFD top CFD bot

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 23

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Backup: Particle tracking

ADCi = ADCtop

i

+ADCbot

i

> thr Reconstructed xy-position from MWPC in the aerogel plane:

200 400 600 800 1000 1200 1400 1600

300
200
100

100 200 300 x' [mm] y' [mm]

The hit distribution in ToF walls:

Hit G [paddle] 5 10 15 20 25 Counts 1000 2000 3000 4000 5000 6000 7000 8000 9000 Hit H [paddle] 5 10 15 20 25 Counts 500 1000 1500 2000 2500 3000 3500

Celli = [X min

i

< x′ < X max

i

] ⊕ [G min

i

< hitG < G max

i

] ⊕ [Hmin

i

< hitH < Hmax

i

]

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 24

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

[Cell0 ⊕ {ADC0 > ADCthr}] ⊗ [Cell1 ⊕ {ADC1 > ADCthr}] ⊗ [Cell2 ⊕ {ADC2 > ADCthr}] ⊗ [Cell3 ⊕ {ADC3 > ADCthr}] ⊗ (1) [Cell4 ⊕ {ADC4 > ADCthr}] ⊗ [Cell5 ⊕ {ADC5 > ADCthr}] F(ADCi) = ADCmax exp(−(ADCi − ADCthr)/ADCwid) + 1 [Cell0 ⊕ {F 2(ADC0) > 1}] ⊗ [Cell1 ⊕ {F 2(ADC1) > 1}] ⊗ [Cell2 ⊕ {F 2(ADC2) > 1}] ⊗ [Cell3 ⊕ {F 2(ADC3) > 1}] ⊗ (2) [Cell4 ⊕ {F 2(ADC4) > 1}] ⊗ [Cell5 ⊕ {F 2(ADC5) > 1}]

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 25

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Backup: Test with various particles

A clear separation between particles above/below emission threshold (protons and positrons):

0.0 0.5 1.0 1.5 5 10 15 20 ADC SUM [Nr. photo−electrons] βTOF

Eff. of each segment vs. β @ 1.5 p.e. AC cut

condition (data taken @ 720 MeV/c cent.

mom. with protons and pions):

β 0.2 0.4 0.6 0.8 1 1.2 Eff [%] 10 20 30 40 50 60 70 80 90 100 Cell 1 Cell 2 Cell 3 Cell 4 Cell 5

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 26

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Backup: Test with positrons at lower beam-current

ADC SUM at I = 300 nA:

5 10 15 20 500 1000 1500 2000 Counts ADC SUM [Nr. photo−electrons]

Efficiency at I = 300 nA:

cut condition [Nr. photo-electrons] 0.5 1 1.5 2 2.5 3 3.5 4 Eff [%] 10 20 30 40 50 60 70 80 90 100 Cell 1 Cell 2 Cell 3 Cell 4 Cell 5

- I = 300 nA

2

Kaos Cent. Mom. = 900 MeV/c -- E beam = 1.5 GeV/c

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 27

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Backup: Test with kaons

Coincidence-time between KAOS and SpekB (with kaon dE/dx and TOF cut) with and without aerogel cut:

[ns]

BG

T

10
5

5 10

Counts

200 400 600 800 1000 1200

Coinc. time SpekB - Wall G

w/o aerogel cut w/ aerogel cut [ns]

BG

T

10
5

5 10

]

2

[MeV/c

x

M

1060 1080 1100 1120 1140 1160 1180 1200 1220 1240

5 10 15 20 25

Coinc. time SpekB Wall G vs. Missing mass w/o aerogel cut

[ns]

BG

T

10
5

5 10

]

2

[MeV/c

x

M

1060 1080 1100 1120 1140 1160 1180 1200 1220 1240

5 10 15 20 25

Coinc. time SpekB - Wall G vs. Missing mass w/ aerogel cut

The mass in the hadron arm with kaon dE/dx, TOF, coinc-time and AC cut: m = p

1

β2 − 1

500 1000 100 200 300 400 500

Counts mass [MeV/c 2]

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 28

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Backup: Kaon electro-production cross-section

dσ dEe′dΩe′dΩ∗

K

= Γv dσv dΩ∗

K

. (3) Γv = α 2π2 Ee′ Ee kγ Q2 1 1 − ǫ , (4) ǫ =

1 + 2|q|2

Q2 tan2 θe 2 −1 (5) dσv dΩ∗

K

= dσT dΩ∗

K

+ ǫ dσL dΩ∗

K

+

2ǫ (1 + ǫ) dσLT

dΩ∗

K

cos φ + ǫ dσTT dΩ∗

K

cos (2φ) + h

2ǫ (1 − ǫ) dσLT ′

dΩ∗

K

sin φ, (6)

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 29

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Proper tracking and PID is needed for particles produced by physical reactions. Reconstructed xy-position from MWPC in the aerogel plane: x′ = x0 + d tan ϑ, y′ = y0 + d tan φ, q

d Dx= d tan x

x=0

z q

MWPC Particles are identified by their energy-loss dE/dx and velocity β = v/c:

TOF

β 0.2 0.4 0.6 0.8 1 1.2 1.4 wall [MeV/cm]

TOF

dE/dx G 2 4 6 8 10 12 5 10 15 20 25 30

TOF

β 0.2 0.4 0.6 0.8 1 1.2 1.4 wall [MeV/cm]

TOF

dE/dx H 5 10 15 20 25 10 20 30 40 50 60 70 80

In the example above: positrons: violet protons: red

L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 30

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Backup: Calibration

R877-100 PMT raw ADC histogram:

Mean 74.69 RMS 17.94 ± 189.9 Integral 2.054e+06 / ndf

2

χ 3.567e+04 / 1075 p0 1.8e+04 ± 1.7e+05 p1 11.5 ±

365.5

p2 2.1 ± 154.8 p3 2.22e-08 ±

8.49e-07

p4 0.00005 ± 0.00224 p5 0.038 ±

2.047

p6 8.8 ± 703.9

TOP ADC 5 [cnts] 200 400 600 800 10001200 Counts

2

10

3

10

4

10

5

10

Mean 74.69 RMS 17.94 ± 189.9 Integral 2.054e+06 / ndf

2

χ 3.567e+04 / 1075 p0 1.8e+04 ± 1.7e+05 p1 11.5 ±

365.5

p2 2.1 ± 154.8 p3 2.22e-08 ±

8.49e-07

p4 0.00005 ± 0.00224 p5 0.038 ±

2.047

p6 8.8 ± 703.9 KAOS/Cerenkov/TOP/Raw 5

calibration fit: p0 exp

− (x − p1)2

2p2

2

+ p3x3 + p4x2 + p5x + p6
L. Debenjak

Implementation and performance analyses of the Cherenkov counter

SLIDE 31

Introduction Aerogel Cherenkov counter Simulations in SLitrani Data analysis and results Overview

Backup

Threshold momentum vs. refractive index:

500 1000 1500 2000 2500 3000 1 1.02 1.04 1.06 1.08 1.1 pthr [MeV/c] n kaons pions

L. Debenjak

Implementation and performance analyses of the Cherenkov counter