activities in mainz

MUV WG meeting. CERN 15.12.2010

Activities in Mainz

David Lomidze, Andreas Winhart

Universität Mainz

MUV working group meetingCERN 15 Dec 2010


Outline

• Investigation of properties of Protvino scintillator using:– Cosmics– Laser– Radioactive Source– LED system

• Automatic test line for mass-test • Setup for Prospective PMT test


Laser setup

Advantage: well defined pulses, fluctuations canceled by energy diode

Disadvantages: Low rate (10Hz), Scintillator must be unwrapped

PM_L PM_R

Ultraviolet Nitrogen Laser

Wavelength 337 nm

Mimics p-Terphenyl

UV Laser Generator

Light distributor

Nitrogen Source

Trigger diode

Filter

Energy diode

Reflector


Setup for PMT photo window uniformity

x

y

~20% fluctuation expected


PM surface scan

~20% fluctuation of PMT photo window as expected


Sr90 Setup

A&B – Read out PMTs

T1&T2 – Trigger PMT

St – Trigger Scintillator, 0.5mm Thickβ energy end point

0.5 / 2.3 MeV

A B

T1 T2

Sr90

St

Collimator

Advantages: High rate ~1KHz (High speed for testing)

Disadvantages: Difficult for energy calibration, Wide range of energy, because of β spectrum nature


Sr90 SpectrumTypical Beta energy distribution

Mean value and area under curve can be used as relative estimators for strip quality

Measured beta spectrum, from two different PMT

Full spectrum of Sr90

Theoretical

Experimental


Sr90 Collimator (Electron Spectrometer)

FieldSN

CurrentForce

Sr90

First Collimating hole

Hole for Magnet

Second Collimating hole

+ -

NS

Magnet

Threshold

At this moment this is at just an idea, but we will try to realize it!


LED system

Several LED with different wavelengths

• 270 μm – to activate p-Terphenyl

• 337 μm to mimic Laser

• 490 μm to mimic WLS fiber light (for mass test of PMTs)

Work in progress on ultrafast LED driver:

1.5ns pulse rise/fall time

Variable pulse length (6ns – 200ns)

Variable pulse size (few mV to 10V)

Variable rate from few Hz up to 100 MHz (for PMT)


LED system

There are few ways for long scintillator tests with LEDs:

Put several LEDs under scintillator (Very fast but expensive way (~170€ each LED))

Drive light from one LED with bundle of clear fibers

Move one LED along scintillator by stepping motor (Bit slow, but low cost way)


Automatic line for mass-test

Cosmics Trigger

Laser


Intermediate box for merging Windows and Linux applications

Why needed it?1. Stepping motor controller application needs windows platform and DAQ is

running under Linux SLC4• But… IT650Flash controller has 4 bit input port, which can be used for CAMAC TTL

signals to control it

2. Extremely high noise - when motor is powered– Few power supply filters have been tried unsuccessfully to solve it

– No noise if motor is disconnected from controller

Way out – intermediate box

24V relies – to disconnect motor before data taking till next movement

Auto operation mode

RS232 serial connector for automatic control by CAMAC – to generate 4 bit signals + one control line to activate/deactivate relies

Manual operation mode


New Mask

• While testing of several samples – observed, that coupling can influence measured Nphe– Main problem -> sometimes not having same length of free

fibers after gluing on each side of scintillator sample (~1/2 mm)

• To exclude geometrical fluctuations:– New PMT mask with holder have been designed

Features:

1. Always 90o angle between WLS fiber and PMT Photo Window (PPW)

2. Keeping end of fibers always at same distance from PPW

3. Variable distance between fibers ends and PPW


Measurement with Laser

X10 cm

Npe

# of Photo Electrons VS Scintillator length

Lowest signals from central region ~8.3 Photo electrons from single PM

But ~16phe from sub-channel and 12x16=192phe longitudinal channel

1900 x 40 x 10 mm3 scintillator sample with two glued fibers


Study of relative light output in WLS fibers using laser

400 x 40 x 10 mm3 Scintillator sample

•One end read-out by 5mm thick plexiglas

•Other end by two WLS fibers, glued along strip

90 x 2 = 180 Phe = total Blue light

12 Phe in two WLS fibers, Green light

~6.6% of light in two WLS fibers


Study of relative light output in WLS fibers using laser

90 x 2 = 180 Phe = total Blue light

12 Phe in two WLS fibers, Green light

~6.6% of light in two WLS fibers

(Fiber trapping Efficiency (5-6%)

&

PMT Quantum efficiency plays significant role)

Quantum efficiency ~16% (at 500nm) (~28% at 390nm)


Wrapping test

Wrapped

Unwrapped

Light output doubled!


Summary table of cosmic test of WLS fibers

Npe

Fiber type Nr of Fibers R2076 R1924A R6095

Bicron 1.2mm MC Round 3 5.3 16 14

Bicron 1.2mm MC Round 2 8 16 6 11.3 6.5 14

Bicron 1.0mm MC Round 2 4 9 3.5 7.2 3.5 7.5

Kuraray 1.0mm MC Round 2 10 21 8.4 17.6 9.5 19.3

Bicron 1.2mm MC Square 2 4 8.2 3.8 7.7 4 8

Bicron 1.2mm MC Round 1 8.9 7.6 9.12

Bicron 1.0mm MC Round 1 5 6 5.4

Kuraray 1.0mm MC Round 1 10.5 10.5 11.9

Bicron 1.2mm MC Square 1 5 6.3 6.1

Bicron 1.2mm SC Round 1 6.5 5.2 6.6

Bicron 1.2mm MC R (BCF-91A) 1 7.6 6.3 8.9

Bicron 1.2mm MC Round 2 11.2 9.1 10.1 NOT Glued 1.5X1.7mm^3groveBicron 1.2mm MC Round 2 17.6 13.8 15.4 Glued

Bicron 1.2mm MC Round 2 10.7 8.3 9 NOT Glued 1.3X1.5mm^3groveBicron 1.2mm MC Round 2 11.3 8.8 Glued

- Npe from single fiber

- Npe from all fibers


MUV1 single channel design

• Considered fibers for single channel construction:– Single Kuraray or Two Bicron 1.2mm round MC fibers

• 2XBicron delivers ~40% more light than single Kuraray fiber• two fibers are more safe

• Wrapping – significant improvement for light collection

• Gluing gives ~50% more Photo electrons• Groove size for 1.2mm fiber – 1.5 x 1.6 mm^2• Number of Grooves = 2


Outlook

• Test setup for 1000 scintillator test: Ready with laser Ready with Sr90 full spectrum– Laser alternative way – LEDs getting ready

• LED driver – experts are involved, already have a prototype– Put threshold on Sr90 spectrum –work in progress (designed first

prototype, needs modifications)• MUV1 PMTs test:

Laser system ready!– LED system in way of development

• MUV2 PMTs– HAC PMTs recently moved to Mainz, quality test will start after

New Year

• Scintillators with final dimensions needed asap!– additionally we NEED to have low quality scintillators

(bubbles, dust, low or high fraction of scintillation material) to check quality/efficiency of our system

activities in mainz

Documents

protvino scintillator

scintillator sample

led systemseveral led

long scintillator tests

pmt photo window uniformityxy

control line

high rate

high noise