1 cosmic rate overview 17.07.2007 rustem dzhelyadin (cern&ihep, protvino) the set-up:...

1

Cosmic Rate Overview

17.07.2007 Rustem DZHELYADIN (CERN&IHEP, Protvino)

The Set-up:

• Scintillating counters HV setting

• Coincidence adjustment

• Accidentals rate

The Vertical Rate measurement:

• on Surface

• in Cavern

The Horizontal Rate measurement:

• Showers suppression

• in Cavern center

• in between HCAL halves

• in muon filter

Results interpretation

2

Cosmic Rate The Set-up


2 scintillating counters WxL=20x60 cm2 used for μ–trigger at beam-test

PMT (FEU-118, 2” diameter, low noise)

NIM crate:

discriminator LeCroy 620AL, 31mV thr., 30 ns shaping

coincidence LeCroy 465, 30 ns shaping

scalers CAEN N145

HV supply CAEN N472 (Umax=2kV, Imax=3mA)

2 standard CERN delay units 63,5+3 ns in 0.5 ns steps

VETO counter WxL=14x100 cm2

3

HV2 = 1,85 kV

1

10

100

1000

1,4 1,5 1,6 1,7 1,8 1,9 2,0

HV1, kV

Rat

e, H

z

S1

S2

S1*S2

Cosmic Rate The HV selection


HV1 = 1,75 kV

1

10

100

1000

1,4 1,5 1,6 1,7 1,8 1,9 2,0HV2, kV

Rat

e, H

zS1

S2

S1*S20.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

1.4 1.5 1.6 1.7 1.8 1.9 2.0

HV3, V

S12

3/S

12

HV1 = 1,8 kV HV2 = 1,8 kV HV3 = 1,85 kV

HV1=1,80 kV HV2=1,75 kV

All measurements done with cosmic at surface

S1*S2*S3/S1*S2

4

Cosmic Rate Vertical integrated flux


S1

S2

At surface

Rs=175.1 Hz/m2

With 5 cm lead on top

RsPb=151.2 Hz/m2

At sea level: 1 count/min/cm2=167 Hz/m2

(CERN is ~400 m above)

In cavern

42

1

3

R1=3.3 Hz/m2

R2=1.9 Hz/m2

R3=1.4 Hz/m2

R4=0.9 Hz/m2

Under HCAL

5

Cosmic Rate Vertical differential flux


S1

S2

At surface

Is=102.4 Hz/m2/sr

In cavern

2

I2=0.72 Hz/m2/sr

109

S1

S2

6

-2.0

-1.5

-1.0

-0.5

0.0

0.5

-50 -40 -30 -20 -10 0 10 20 30 40 50

nsV

Cosmic Rate Accidental coincidence rate


Single counter rate (after shaper) was permanently recorded (N1, N2 ) 1. Accidental Rate evaluated :

Nacc = 2 N1 N2 = 30 ns (shaping time)

2. Accidental Rate measurement:

T Nacc = S1 (delay 155 ns) x S2 T – measurement time

Shaping time was chosen 30 ns to exclude counters signal jitter at distances ≤ 2m

( ± 10 ns )

Typical single counter Rate was N ~ 30-100 HzBoth measurements coincide within statistical error

7

Cosmic Rate Set-up modification


S1

S2

A3

Rates are lower: a VETO counter ( A3) used to suppress -showers

-2.0

-1.5

-1.0

-0.5

0.0

0.5

-40 -30 -20 -10 0 10 20 30 40 50 60

ns

V

A3

S1*S2

8

Cosmic Rate Set-up modification


S1

A3

10 4

2.5

Geometry allow particleto cross S1 and S2without VETO at distances as low as

40 cm between S1 – S2

Measurements donewithin range

D = 40.5 ÷ 182.7 cm

9

Cosmic Rate Angle definition


θy

(All flux) = 3 x (Trigger condition)

D

10

Cosmic Rate Semi-horizontal flux


0.00010

0.00100

0.01000

0.10000

1.00000

0.01 0.10 1.00

sin(q y )

Co

un

tin

g r

ate

for

1/3

S2,

Hz/

m2

123 Similarity trigger condition X Y 1 – 2x2 outer 2 – 2x2 inner or 2x1 outer 3 – 2x1 inner

- between HCAL halves

- around μ-shielding (very preliminary)

S1S2

It looks like in air soft μ - dominating fluxdue to multiple scattering (?)

Surface, m2

inner = 15.17outer = 41.93

11

Cosmic Rate Summary


Counting rate per day (86 400 s) in HCAL:

Ninner = 0.016 Hz/m2 x 15 m2 x 8.6•104 = 2•104

Nouter = 0.050 Hz/m2 x 40 m2 x 8.6•104 = 17•104

weak muons

Ninner = 0.0009 Hz/m2 x 15 m2 x 8.6•104 = 1.2•103

strong muons

Nouter = 0.0046 Hz/m2 x 40 m2 x 8.6•104 = 16•103

Extrapolation according to Sin3(Θy )

… to be measured, checked for muon showers, …

1 cosmic rate overview 17.07.2007 rustem dzhelyadin (cern&ihep, protvino) the set-up:...

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