Design, construction and characterization of a large area/high efficiency thermal neutron - PowerPoint Presentation

Slide1

Design, construction and characterization of a large area/high efficiency thermal neutron BAND-GEM full module detector

1

G.Croci

2,1,3

,

A. Muraro

1

,

E

. Perelli Cippo

2,3

, M.Tardocchi

1,3

, G.Grosso

1

,

M.Rebai

2,3

,F. Murtas

4

, R. Hall-Wilton

5,6

, C. Höglund

5

, L. Robinson

5

, K. Kanaki

5

, D. Raspino

7

, E. Schooneveld

7

, N. Rodhes

7

, I. Defendi

8

, K. Zeitelhack

8

, A. Abba

9

and

G.Gorini

2,1

1

Università

di Milano-Bicocca -

2

INFN–Milano-Bicocca -

3

IFP-CNR

, Milano

-

4

LNF-INFN

,

Frascati

–

5

ESS ERIC, Lund, Sweden –

6

Mittuniversitetet,

Sundsvall

,

Sweden

–

7

STFC-ISIS

Facility, Rutherford Appleton Laboratory, Didcot,

UK –

8

Heinz

Maier-Leibnitz Zentrum (MLZ),

TUM

Garching,

Germany-

9

Nuclear Instruments

Slide2

Outline

Boron Array Neutron Detector (BAND)-GEM principleDesign, construction and performance of small area BAND-GEM detectors

Full module as a detector option for LOKI@ESSConclusions2

Slide3

Motivation

3

European Spallation Source (ESS) will

provide higher peak neutron fluxes than existing facilities today.

Need of detector with high counting rate capabilities

in the new spallation source

Slide4

The BAND-GEM detector system: an option for LoKI

4

n

beam

Sample position

5 m

3

m

Middle

bank

.

Composed

of 8 BAND-GEM full

module

Front detector

bank

.

Composed

of BAND-GEM

sectors

LoKI is a Small Angle Neutron Scattering experiment under construction at ESS.

A high neutron flux (up to 4∙10

5

n/cm

2

s) is expected

.

BAND-GEM is one of the possible option for the instrumentation of this beamline.

Tubes (SWPC) based solution are not suitable

Requirements

for LOKI detectors

Rate Capability

> 200 kHz / cm2

Time Resolution< 1 msX-Y space resolution4 mmEfficiency 50 % at 6 Å.

Requirements

for LOKI detectors

Rate Capability

> 200 kHz/cm

2

Time Res

< 1 ms

Spatial

Res

About 6 mm

Efficiency

>

35

% @

4 Å

Slide5

BAND-GEM detection

principle

5

Alluminium grids coated on both sides with 10

B4

C

Using low

θ

values (few degs) the path of the neutron inside the B

4

C is increased

 Higher efficiency when detector is inclined

5

cm

96

m

m

4

m

m

Triple GEM

Padded Anode

Cathode

3D

Grid

System

n

α

e-

α

10

B

4

C

10

B

4

C

10

B

4

C

10

B

4

C

n

Al=200µm

Al

θ

E

Grid

E

G

G

8

m

m

Typical tilt angle

Ѳ

=5°

V

Cathode

V

TopGrid

Slide6

BAND-GEM demonstrator: design and construction

6

Triple GEM detector with padded anode

Grids stack (Active area 5x10 cm

2

)

Detector box

The calculations made for the optimization of the BAND-GEM geometry led to the development and the construction of the BAND-GEM demonstrator

Before the deposition process:

After the deposition process:

Re-tensioning with the screws

400°C

It

is

essential

to obtain

VERY STRAIGHT

strips in order to have a good electron extraction efficiency.

Padded anode (3x4 mm

2

)

Slide7

Nominal 1 µm of

10

B

4

C DEPOSITION @ ESS Workshop (Linkoeping)

B4C coating performed @ Linkoeping University

Slide8

Efficiency (

at

1 and 2 A) vs tilt angle

8

Test made @ EMMA (ISIS

)

Slide9

Space resolution (

FWHM) vs

tilt angle

Slide10

Linearity

scan

of BAND-GEM

demonstrator

relative to

Fission

Chamber

,

performed

at

reactor

power

10.1 MW.

The BAND-GEM

is

linear (relative to the

reference

FC detector) up to

about 5 MHz/cm2.

Black dots: BANDGEM count rates per cm

2

; red line: fit of the data with saturation law; purple line: linear component of the saturation law.

V

cathode

-V

TopGrid

= -10

kV

Σ

V

GEM = 870 VTilt angle = 5°

Full beam

1.8 mm attenuator

3.6 mm attenuator

High rate test

at

the ORPHEE

Reactor

@ LLB-CEA

Slide11

Improved BAND-GEM

detection

principle

11

Aluminum

grids coated on both sides with

10

B

4

C

Using low

θ

values (few degs) the path of the neutron inside the B

4

C is increased

 Higher efficiency when detector is inclined

96 mm

4 mm

Triple GEM

Padded Anode

Cathode

3D

Grid

System+ middle GEM

n

α

e-

α

10

B

4

C

10

B

4

C

10

B

4

C

10

B

4

C

n

Al=200µm

Al

θ

E

Grid

E

GG

8 mm

Typical tilt angle Ѳ=5°

3mm

1

mm

V

Cathode

V

TopGrid

Slide12

Improved

BANDGEM demonstrator

Slide13

Observed Improvement on the extraction efficiency

z

y

Extraction efficiency from the 3D grid system was improved by the insertion of the middle GEM

Study performed by shooting the neutron beam from the side through a diagnostic window

Slide14

Efficiency vs neutron wavelegnth

λ

14

Test made @ CRISP (ISIS)

Slide15

BAND-GEM full-module: CAD overview

15

Detector BOX

Front of the detector

GEMINI Chips Used (see A. Abba talk)

Slide16

Full Module Detector: ReadOut

Anode

16

Total

n°of

channel

:

1472

Slide17

BAND-GEM full-module: design and construction

17

The 3D-C assembled

The GEM foil

The padded anode

Slide18

Test of the full-module @ TREFF

Neutron beam

BAND-GEM

Monochromatic neutrons with wavelenght

λ

=4.78 Å

BAND-GEM with GEMINI electronics

Slide19

Working Point determination

V

cathode

Scan

V

TopGrid Scan

V

TripleGEM

Scan

V

MiddleGEM

Scan

Slide20

Uniformity of the detection efficiency

Working Point

Vcathode = -14 kV

V

MiddleGEMBottom

= -8.75 kVV

MiddleGEM Top

= -8.48 kV

V

TopGrid

= - 5 kV

V

GEM1Top

= -2.7 kV

E

T1

=E

T2

= 5 KV/cm

E

ind

= 5 kV/cm

ΣΔ

GEM = 900 V

PRELIMINARY

Tilting angle Ѳ between 1° and 2°

Slide21

Efficiency vs

neutron

wavelength @EMMA

Tilting angle

Ѳ

=

8

°

Slide22

Spatial resolution

vs neutron

wavelength

Slide23

Test of the full-module @ LARMOR beam line (SANS instrument). Preliminary results.SANS measurement performd with a

concentrated ludox silica dispersion sample. With this sample, the expected 2d map on the detector position is a circular ring

moving to larger radius at longer wavelengths.

Neutron beam

Sample

BAND-GEM

1,5 m

BAND-GEM full module with Cd mask

Slide24

Test of the full-module @ LARMOR beam line (SANS instrument). Preliminary results.

C

ircular ring

Slide25

Conclusions

The test made with neutrons have shown that the BAND-GEM technology allows a neutron detection efficiency > 40% for

λ≥2 Å and is able to sustain the high rate expected at ESSThe BAND-GEM full module was designed during 2017 and realized at the beginning of 2018

The tests with neutrons performed with the BAND-GEM full module have shown that the detector has performace similar to what was obtained with the small BANDGEM demonstratorsThe BAND-GEM full module was also tested in a real SANS experiment and t

he data analysis is still ongoing.

Even if all the requirements for LOKI were satisfied,

the experiment board DID NOT select the BANDGEM detector

option for

LOKI.

A

straw

tubes based solution

was preferred.

Slide26

Thank you26

Slide27

EGEM<100 kV/cmE

D,ET1E

T2  3 kV/cmEi  5kV/cm

Triple GEM

for thermal neutrons

Ar/CO

2

70/30%

Q=2.31

MeV

E

Li

=0.84

MeV

E

α

=1.47

MeV

σ

abs

=3840 b (E

n

=25

meV

)

Back to back

emission

α

range(B4C)≈3.4 µmLi

range(B4C)≈1.7 µmPerformance obtained with the bGEMInsensitive to gamma rays

Rate capability up to 50 MHz/cm

2 [*]Low efficiency (≈2.5% @ 2 Å)

[*] E. Perelli Cippo et al,’’

A GEM-based thermal neutron detector for high counting rate applications’’, JINST October 2015

Slide28

BAND-GEM demonstrator: CAD model and assembly

Middle GEM (active area 5x5 cm

2

)

12 grids

Middle GEM

12 grids

11 grids

Detector BOX

TripleGEM

Padded anode (3x4 mm

2

)

28

Slide29

BAND-GEM demonstrator: x-rays tests

E field with 4700 V

E field with 10700 V