[PPT] - DUNE APA Requirements study Yichen Li Brookhaven National PowerPoint Presentation

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DUNE APA Requirements study

Yichen Li Brookhaven National Laboratory DUNE APA Consortium Meeting 04/30/2018 DUNE-doc-7899-v1

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The Deep Underground Neutrino Experiment (DUNE) is planning for one or more
f the first two 10 kt detector modules with Single-Phase LArTPC Design.
The Anode Plane Assembly (APA) is a crucial detector component, which is

responsible to detect the induced currents from drifting ionization electrons. There are 150 APAs per one 10 kt DUNE far detector module.

The APA production is distributed at different production sites in multiple

countries.

The quality control (QC) of the APA production is crucial to the success of the

project

So far, there is only one general requirement related to the APA: <1% overall

non-functional channels. Equally split between the APA and electronics, then we have < 0.5% APA related non-functional channels for DUNE detector module which is not sufficient to serve as the QC guideline

We define additional technical requirements as a guideline for the APA

production QC

DUNE APA Technical Requirements

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Deviations from the ideal APA geometry (change in wire plane gap distance,

wire locations, missing wires) can lead to: —Non-100% transparency of ionization electrons ->collection type signal on induction wire planes —Change of field response functions

> increase in charge resolution

increase in energy resolution (impact can be reduced with calibration)

While the increase in charge resolution is not desired, the non-100%

transparency of ionization electrons are much more dangerous for overall event reconstruction —We thus focus on the requirement of APA geometry with the primary consideration on the transparency conditions which requires 100% drifting ionization electrons to pass through the grid (G) and induction (U and V) planes.

Discussion on Method

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4.76mm 4.79 mm Diameter 150 um

U V X

370V

0 V +820 V

4.76 mm

G -665V

4.667 mm 4.667 mm 4.79 mm 4.76mm 4.76mm

Ground plane0 V

Simulation Scheme in Garfield

Garfield-2D is used for the electron drifting simulation
DUNE APA wire configurations defined in 2D
50-100 electrons 30 mm above the X plane, parallel to the wire plane, covering

across 2 or more pitches, are configured 

Drift field is at 500 V/cm

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Normal Scenario

We first run the normal scenario as a baseline
The normal conditions indicates 100% transparency on U and V, 100 %

collection on W

In reality, multiple issues may cause the deviations from an ideal APA

geometry, e.g.: 

1. Mechanical precision in wire winding 
2. Distortion of the wire frame 
3. Weight of the wire

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U plane shift (aligned)

Informed by the APA production team, the wire positions are expected to be

controlled within 0.5 mm precision.

First shift U plane for 0.5 mm up and down, 100% transparency still holds
With aligned wires, 100% transparency still holds with wire shift up/down to

1.0 and 2.0 mm

U+0.5 mm up U-0.5 mm down U+2.0 mm down

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U plane shift (pitch shift)

First shift U plane horizontally in plane by 1/2 pitch, 100%

transparency still holds

U shift 1/2 pitch

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First shift U plane in plane by 1/2 pitch+shift up by 0.5 mm,

100% transparency still holds

U plane shift(pitch+plane shift)

U shift 1/2 pitch and +0.5 mm up

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First shift U plane in plane by 1/2 pitch+shift up by 0.5 mm, shift G plane

down by 0.5 mm, 100% transparency breaks, 2 electrons are collected on U

U Transparency reduces to ~ 96%
With further plane shift up to 2.0 mm, U transparency reduces to ~80%

U plane shift (pitch+plane shift)

U shift 1/2 pitch and +0.5 mm up  G-0.5 mm down U shift 1/2 pitch and +1.5 mm up G-0.5 mm down

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First shift V plane for 0.5 mm up and down, 100% transparency

still holds

With aligned wires, 100% transparency still holds with wire shift

even up/down to 1.0 and 2.0 mm

V plane shift (aligned)

V+0.5 mm up V-0.5 mm up V-2.0 mm up

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Half pitch shift without plane shift holds 100% with 0.5 cm shift
First shift V plane in plane by 1/2 pitch+shift up by 1.0 mm, 100%

transparency breaks, 6 electrons are collected on V, ~88% transparency

Shift up by 2.0 mm, V transparency reduces to ~64%

V plane shift (pitch+plane shift)

V shift 1/2 pitch and +1.0 mm up V shift 1/2 pitch and +2.0 mm up

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4.76mm 4.79 mm Diameter 150 um

U V W

370V

0 V +820 V

4.76 mm

G -665V

4.667 mm 4.667 mm 4.79 mm 4.76mm 4.76mm

Ground plane0 V

Simulation scheme: missing wire

During the APA production, it is possible that certain wires are broken after wire winding

procedure. 

In this case, it is impractical to unwind the wires in order to fix the broken wires. It is possible that
ne solution in dealing with this kind of broken wires is to cut and remove them from the APA. 
50 electron evenly distributed are set, the length of the track are adjusted to the number of

missing wires by covering the whole range where the wires are missing.

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1 wire missing on the U plane
2 wires missing on the U plane
3 wires missing on the U plane
All the case, the transparency still holds at 100 %
Results more than 3 wires missing is expected to similar

U plane wire missing

missing 1 missing 2 missing 3

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V plane wire missing

1 wire missing on the V plane
2 wires missing on the V plane
3 wires missing on the V plane
All the case, the transparency still holds at 100 %, pretty much similar to U plane

missing wire case

missing 1 missing 2 missing 3

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1 wire missing on the U plane
1 wire missing on the V plane
All the case, the transparency still holds at 100 %

U and V plane wire missing

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W plane wire missing

1 wire missing on the W plane
2 wires missing on the W plane
3 wires missing on the W plane
4 wires missing on the W plane
For collection plane, missing wires seems to be a more serious problem, 100% collection can only

be achieved with 1 wire missing. Collection on V plane is observed for more than 1 wire missing

V Transparency 100% V Transparency ~95% V Transparency ~70% V Transparency ~80% missing 2 missing 3 missing 4 missing 1 16

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The transparency can also be checked with an analytic method described in Bunemann, et al., Design of Grid

Ionization Chambers, Canadian Journal of Research, 1949 

The condition for transparency is that no field lines intercept a grid wire, i.e. no contour at the same

potential as the wire extending from the wire 

Using modified python script from Glenn Horton-Smith (uBoonNE docdb-4708 ) following the Garfield

agrees with the analytic calculation, weak collection on U plane observed as by Garfield

Cross check with analytic calculation

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G U V W

Normal Conditions

G U V W

U pitch and plane shifted 0.5 mm  plane shifted 0.5 mm to U

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Condi&on Transparency Nominal 4.76 mm gap distance 100% Shi9 U plane up by 0.5 mm 100% Shi9 U plane up by 0.5 mm Shi9 G plane down by 0.5 mm 96% Shi9 V plane up by 0.5 mm 100% Shi9 V plane up by 0.5 mm Shi9 U plane down by 0.5 mm ~88% Condi&on Transparency Missing one U wire 100% Missing two U wires 100% Missing three U wires 100% Missing one V wires 100% Missing two V wires 100% Missing three V wires 100% Missing one U and one V wires 100% Missing one X plane wire 100% Missing two X plane wires ~95% Missing three X plane wires ~80% Missing four X plane wires ~70%

Summary

Wire plane gap deviation Missing Wire

If the wire plane gap distance can

be controlled within 0.5 mm, the impact to transparency condition should be small

Requirement: control the wire plane

gap distance to below 0.5 mm

Missing more than one continuous

collection plane wires leads to significant impact on the transparency condition, less impact for missing induction plane wires

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Conclusions

We define the technical requirements on the DUNE Anode Plane Assembly (APA)

geometry based on the consideration of the 100% transparency condition for drifting the ionization electronsWe show: The wire position in terms of distance between adjacent wire planes controlled to within 0.5 mm is acceptable.! The wire pitch between adjacent wires controlled to within 0.5 mm is acceptable.! Missing more than one consecutive wires on induction planes has minimal impact

n the transparency!

Missing more than one continuous wire on collection plane leads to partial collection on induction wire plane, and thus should be avoided.!

These conditions, together with the general requirement of less than 0.5% APA-

related non-functional channels dene the technical requirement on the APA geometry.

See DUNE-doc-7899-v1 for more details

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