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Calibrations. LXe calibrations, PMT tests, cryostat construction. Alpha sources on wires 9 MeV  from neutron capture in Nickel  0 further calibration methods ? PMTs tests Cryostat status. Sorces at different distances seen by each PMT : unique feature Made at Genova INFN

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slide1

Calibrations

LXe calibrations, PMT tests, cryostat construction

  • Alpha sources on wires
  • 9 MeV  from neutron capture in Nickel
  • 0
  • further calibration methods ?
  • PMTs tests
  • Cryostat status
1 alpha sources spots on wires
Sorces at different distances seen by each PMT: unique feature

Made at Genova INFN

electrodeposited ( solution) on a gold-plated W wire

0.5 mm spots 12.4 cm apart (2 PMTs)

Wire thickness: 50 (alpha range ~40  )

Wire suspended with springs

Wires A,B = 100 Bq/source (LP front face)

Wires C,D = 30 Bq/source (LP back face)

A Czech Republic firm can provide a suitable wire in which Am on foils is attached to wires by thermocompression

1) Alpha sources spots on wires

LP Front face

Lateral face

slide5

The ring radius depends on the Rauleigh scattering length

  • The best value for reproducing the radius is 20 cm
  • In contrast with previous estimates!
  • Reflection ? ...we must improve the simulation and detector understanding
slide8

Charge vs Cos in LXe

Front Face

Data

MC

lxe mc
LXe/MC

New PMTs

4 front sources

Old PMTs

lxe mc10
LXe/MC

4 front sources

After applying QEs

towards the final calorimeter
Towards the final calorimeter

70 kHz photons with E>5 MeV from muon radiative decay @ R() 3x10**7. Total sources rate O(15 KBq @ 5 MeV)

slide13

AMERICIUM WIRE-SOURCES

  • World-wide search (from 2003...):
  • ISOTRAK-AEA TECHNOLOGY
  • ISOTOPE PRODUCTS
  • LEA-CERCA
  • NORTH AMERICAN SCIENTIFIC
  • FRAMATOME
  • ETC.
  • all of them refused to consider this custom-made product....!
  • too difficult, too long development, too expensive, etc.

Finally:found a factory,Czech republic, Prague

working on ionization smoke detectors and electrostatic charge eliminators

(8 people.....)

accepted to perform a R&D for our special request.

UP and DOWN SUCCESS !:

Production method by “thermocompression”. Liquid Nitrogen tests at ENEA.

VERY IMPORTANT FOR FUTURE CRYOGENIC LIQUID DETECTORS

unique feature !

slide14

SPECITICATIONS

AND CONTRACT

FOR THE PRODUCTION

OF Am WIRE-SOURCES AND

OF Am DISK-SOURCES

Ready: end of March 2005

(TOTAL ACTIVITY < 40 kBq)

Each dot-source:

small radioative foil fixed on wire by

“thermocompression”

TESTED AT NITROGEN TEMPERATURE

AT THE ENEA LAB. IN ROME. OK !

  • NEEDED FROM PSI:
  • Authorization of nuclear security
  • for products
  • Authorization for import of
  • radioactive sources
  • Auhorization for production of
  • detectors using radioactive sources
slide15

WIRE SOURCES FOR FINAL CALORIMETER

15 WIRES, 5 DOT-SOURCES PER WIRE

150 cm total wire length

12.4 cm distance between Am dots

Central Dot

20.0 cm distance between Mark and First Dot

Am dots

Reference Mark

Wire of 100 micron diameter

Material: gold plated steel or tungsten

Total length 150 cm

Spacing of dot-sources 12.4 cm

Linear dimension of dots 1-2 mm

Activity 200Bq per dot

slide16

WIRE SOURCES FOR LARGE PROTOTYPE

10 WIRES, 2 DOT-SOURCES PER WIRE

150 cm total wire length

12.4 cm distance between Am dots

Wire centre

20.0 cm distance between Mark and First Dot

Am dots

Reference Mark

Wire of 100 micron diameter

Material: gold plated steel or tungsten

Total length 150 cm

Spacing of dot-sources 12.4 cm

Linear dimension of dots 1-2 mm

Activity 200Bq per dot

slide17

WIRE SOURCES FOR PISA DEVICE

2 WIRES, 1 DOT-SOURCE PER WIRE

50 cm total wire length

Reference Mark

Central Am Dot

20.0 cm distance between Mark and Dot

Wire of 100 micron diameter

Material: gold plated steel or tungsten

Total length 50 cm

Central dot-source

Linear dimension of dots 1-2 mm

Dot Activity 200Bq

slide19

rather narrow

energy-spectra

possible mounting

on special

supports and screws

2 9 mev gamma line from neutron capture on nickel experimental set up
2) 9 MeV gamma line from neutron capture on Nickel:Experimental set-up
  • Am-Be source
  • (20000 n/s);
  • Polyethylene;
  • Nickel plates
  • 30 x 30 cm2
  • (0.5 cm and 0.25 cm
  • thickness)
  • 20 x 20 x 36 cm3
  • NaI detector
  • MCAORTEC
  • (2048 channels)
  • NIM electronics.
line from n capture on ni i al h 2 natural radioactivity tl k am be source
γ-line from n-capture on Ni, I, Al, H2; natural radioactivity Tl, K; Am/Be source

K

1.46 MeV

H2

2.2 MeV

Am/Be

4.4 MeV &

1st escape

Ni

8.54 MeV &

1st escape

Tl

2.6 MeV

I

6.8 Mev

Ni

9 MeV

Al

7.7 MeV

Black: Am/Be source and 1 cm Ni

Red: no Am/Be source

Green: no Am-Be source, no Ni

(Gotta Beam on)

slide23

neutron generator (Pavia ?)

20 cm

3 cm

THERMAL NEUTRON CAPTURE ON NICKEL

D + 2H 3He + n Q = 3.27 MeV

D + 3H 4He + n Q = 17.59 MeV

  • Potentialities :
  • switchable on-off
  • frequent (s, m,...) stability checks
  • system out of the calorimeter
  • Ni and Xe, prompt and delayed signals
  • probably: visible signal at full beam intensity
  • time reference

9 MeV Nickelγ-line

  • Open problems:
  • monitoring from calorimeter back
  • only at one location ?
  • some dispersed neutrons and radioactivity
  • test of the method at high beam intensity
  • useful test with the “large prototype”
  • (already foreseen in April, with Am/Be source)

NaI 20 x 20 x 36 cm3

  • Intensities from 106 n/s to 108 n/s
  • Typical pulse rate and pulse width 10 Hz and 1 μs
  • Time separation of direct from delayed reactions
  • Single pulse mode

Polyethylene

0.25 cm Nickel plate

possibilities
Possibilities

POLY

POLY

POLY

POLY

POLY

NaI

n

Am/Be

0.25 cm Nickel

3 cm polyethylene

3 p 0 calibration

How often can it be performed?

3) p0calibration…

Anti Counter

Support structure: straightly up and down

Tilt mechanism at every height for NaI front to face target direction.

tilt

  • Proton beam: 1.8mA
  • Pion Rate: 2x107p-/sec
  • Collimate: 2PMTs x 2PMTs ~ 150cm2
  • (1 position)
  • 2 g/sec
  • # of PMTs on incident face: 216 PMTs (54 positions)
  • required: 30,000 evts/position
  • takes 30,000 x 54 / 2 =
  • 810,000sec~ 10 days

g

Target

up

p0

down

g

target

slide26

3) Further calibration methods...

500 KV PROTON ACCELERATOAND LITIUM TARGET FOR A

17.6 MEV GAMMA LINE

37Li (p,)48Be

[P.R. 73, 666 (1948), N.P. 21 1 (1960), Zeitschrift f. Physik A351 229 (1995)]

  • Potentialities :
  • a unique nuclear reaction with a high energy -line (10 KeV)
  • obtainable :  106 /s (isotropic) at 440 KeV resonance (Ip 50 A)
  • from LiF target at COBRA center; ’s on the whole cal. entrance face
  • energy and position calibration; shower properties; all over LXe cal.
  • possibly: rather frequent use
  • Open problems:
  • compatibility with normal beam and target ?
  • project for easiness of target-tube mounting
  • accelerator/COBRA, which position and distance ?
  • p-beam divergence and protons on target; p29 MeV/c
  • 500 KeV and criticality of an air-insulated accelerator
  • is a post-acceleration possible ?
slide28

37Li (p,)48Be

resonant at Ep= 440 keV

=14 keV peak = 5 mb

E0 = 17.6 MeV

E1 = 14.6

6.1

Bpeak 0/(0+ 1)= 0.720.07

NaI 12”x12”  spectrum

Crystal Ball Data

0

1

slide29

Cecil et al. NP A539 75 (1992)

10x10 cm NaI crystal

A further interesting possibility...

511B (p,)612C

resonant at Ep= 163 keV

= 7 keV

E0 = 16.1 MeV peak = 5.5 b

E1 = 11.7 + 4.4 peak = 152 b

  •  7500/s (isotropic)
  • 20.0001/s for Ip 50 A

lower proton energy !

lower rate at 50 A !!

slide30

NOW: GLAST SPACE EXPERIMENT

CRYSTAL CALORIMETER CALIBRATION

180 cm target-pipe

It is the old VDG of the Crystal Box experiment ! !

they have some problems: old device, max. VDG p-energy is 400 KeV

out of resonance: -rate reduced by factor  5000

How can we get one such device ?? We are exploring several possibilities...

slide31

Cal. calibration from the target position,monitoring at the cal. back

rails

cockroft

focusing elements

(magnetic or electrostatic ?)

at the cal. back the proton motion in the COBRA field must be be studied

proton mc tra jectories e p 440 kev 28 mev c
proton MC trajectoriesEp 440 keV 28 MeV/c!!

Y(cm)

the protons are not

reflected back by the

varying magnetic field

Θ ~ 8 giroradius < 12 cm

X(cm)

Z(cm)

slide33

Plane Z = 0 cm

Y(cm)

ρ ~0.8cm

X(cm)

Θ ~ 0.5 giroradius < 1 cm

Z(cm)

slide34

KEEP MEG UNDER CONTROL

PARTICULARLY AT HIGH (AND VARIABLE) BEAM INTENSITIES.........

BR   eg~10-13

Beam Intensity~5 107 /s

  • frequent checks of calorimeter energy scale, linearity and stability
  • checks of LXe optical properties
  • energy resolution and spacial resolution
  • shower properties
  • at the right  energy ( 53 MeV), but also at other energies.....

no single calibration method has all the required characteristics

use complementary (and redundant) methods,

make the best use of their intrinsic properties

emphasize the reliability of our experiment

5 pmt tests
5) PMT tests

PMT in LP, LED pulsed (@ 1 khz)

F18, TB type

F0, 6041 (old)

<Q>= 50 pC

<Q>= 87 pC

10 khz
10 Khz

TB

6041

<Q>= 50 pC

<Q>= 87 pC

photocathode saturation effect

50 khz
50 Khz

6041

TB

<Q>= 50 pC

<Q>= 87 pC

photocathode saturation effect

100 khz
100 Khz

6041

TB

<Q>= 50 pC

<Q>= 87 pC

Gain non linearity

slide39
6041

t = 115 s

Anode current should be < 0.5 mA

slide40
TB

Lower photocathode resistivity (ZA much better)

linearity much improved
Linearity much improved

presently installed

T=-108ºC

PMT with Zener

but zener problem at low temperature
Positive pulses with total positive charge are seen! (rate ~300 Hz @ V>20 mV)

The problem is present ONLY at liquid Xe temperature: disappears during warm-up

The pulse is not present when the Zener diodes are removed

But … Zener problem at low temperature
r9288 base with low pass filter
R9288 base with low pass filter
  • Low pass filter is built in
  • by adding resistors serial to Zener
  • If the resistance is too small, filtering will not work.
  • With too large resistance, the effect of Zener will be little
  • under high rate BG environment

Optimum resistance will be something

around 100KOhm

low pass filter in pmt base @ astro e2 hxd
PMT base with Zener diode and low pass filter is adopted in Astro-E2 Hard X-ray Detector. (HXD)

Fifth Japanese space X-ray observatory

PMT+BGO

High counting rate

HXD will be cooled downed to –30 °C

Low pass filter in PMT base @ Astro-E2 HXD

Zener is used in this base circuit and low pass filter is built in because of the noise from Zener. Various tests have been performed with this base and its good performance was confirmed so far.

chamber set up

Type Z

Chamber Set Up

Upper PMT temp.

~ - 85 °C

HV=800V for both PMTs

Same interstage volt.,

same current between 2 PMTs

Alpha source

LED

Type ZR

Gas

xenon

Lower PMT temp.

~ - 100 °C

oscilloscope snapshot
Oscilloscope Snapshot

Noise from Zener

Type Z

No noise was observed!!

Alpha event

Type ZR

Yasuko HISAMATSU MEG Collaboration Meeting Feb. 2005

if the base type zr doesn t work
If the base Type ZR doesn’t work…
  • We have an alternative; active base with MOS-FET
  • Adopted in the πβ experiment
  • MOS-FET is operational in 165K
when a solution is found
When a solution is found

Start testing PMTs: 300-400 at Pisa (Cryo facility) and 600-700 at PSI (LP)

slide53

6) Cryostat: designs ready; tenders and procurements organization

  • Tenders have been organized in three parts:
  • Conventional part
  • Cold and warm windows
  • Purchasing of the cold sealing
  • PMTs supporting structure
  • The tender procedure has been completed for the conventional part.
  • SIMIC has won the tender for the best price and for other reasons.
  • This company is going to purchase a low magnetic permeability stainless steel (<1.008) and will perform the cold test at the company. We visited the company to warn them about the project difficulty, remarking our requirements in term of level of cleanness and tightness written in the tender technical specification.
  • The company, if it will receive in time the cold and warm window and the cold sealing, estimated a fabrication time of 10th month.
slide54

SIMIC profile in cryogenics application

http://www.simic.it/eng/home.htm

slide55

Cold and warm windows

  • FEA studies are in progress.
  • Honeycomb structure has been discussed with manufacturing companies
  • We are trying to subdivide the fabrication and qualification of the window to be able to maintain the cost as low as possible
  • We have separated the following activities.
  • Mechanical test ( Mech. Dept Univ of Pisa)
  • Test box and welded parts (Mechanical design INFN (Pisa) manufacturing with proper company)
  • Tooling and molds are going to be designed by INFN (Pisa)
  • Honeycomb structure (Composite aerospace company)
slide57

Honeycomb structure discussed with manufacturing company

Honeycomb structure

Two facing of .7 mm CFRP.

(intermediate high module CF with

Epoxy space approved)

Core aluminum honeycomb

perforated

This area is reinforced

Internal welded foil .3 mm or less welded on external

Frame necessary to test the window prior the final welding on the cryostat body.

Bolted area

slide58

Honeycomb structure has been discussed with manufacturing company

Using thin facing material makes difficult to obtain high tolerance, even if we use a flex core material, not available in perforated aluminum.

This area is reinforced

Precision must been obtained on this side for this reason the honeycomb must rest on the mold on this side

slide59

Cold joints: interaction with the factory

Modification of bolts position and number

We asked non-magnetic seal

slide62

Some issues recently reviewed

  • Detailed drawings of internal attachments
  • Windows area dimensions reviewed.
  • Superinsulation required to the company
  • Electro polishing of internal surfaces
  • Outer vessel isolated from the base. (A G10 plate will be placed under the cryostat legs)
  • Reviewed the height of all components
  • Metallic o-rings to be fixed in the vertical position
  • Guiding pins needs to be added on the cold and on the warm flange to avoiding that the studs are hitting the contact surface of the o-ring on the covers
slide63

2005

Calorimeter schedule