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

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

DUNE APA Technical Requirements • The Deep Underground Neutrino Experiment (DUNE) is planning for one or more of 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 2

Discussion on Method • 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. 3

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 
 4.79 mm G -665V 4.667 mm 4.76mm U - 370V 4.667 mm 4.76 mm V 0 V 4.79 mm 4.76mm X +820 V 4.76mm Ground plane 0 V Diameter 150 um 4

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 5

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 U+2.0 mm U+0.5 mm down down up 6

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 7

U plane shift(pitch+plane shift) • First shift U plane in plane by 1/2 pitch+shift up by 0.5 mm, 100% transparency still holds U shift 1/2 pitch and +0.5 mm up 8

U plane shift (pitch+plane shift) • 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 shift 1/2 U shift 1/2 pitch pitch and and +1.5 mm up +0.5 mm up 
 G-0.5 mm G-0.5 mm down down 9

V plane shift (aligned) • 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-0.5 mm V-2.0 mm V+0.5 mm up up up 10

V plane shift (pitch+plane shift) • 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 shift 1/2 V shift 1/2 pitch pitch and and +1.0 mm up +2.0 mm up 11

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 one 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. 4.79 mm G -665V 4.667 mm 4.76mm U - 370V 4.667 mm 4.76 mm V 0 V 4.79 mm 4.76mm W +820 V 4.76mm Ground plane 0 V Diameter 150 um 12

U plane wire missing • 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 missing 1 missing 2 missing 3 13

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 14

U and V plane wire missing • 1 wire missing on the U plane • 1 wire missing on the V plane • All the case, the transparency still holds at 100 % 15

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

Cross check with analytic calculation • 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 U pitch and plane shifted 0.5 mm 
 Normal Conditions plane shifted 0.5 mm to U G U G U V W V W 17

Summary Wire plane gap deviation Missing Wire Condi&on Transparency Condi&on Transparency Missing one U wire 100% Nominal 4.76 mm gap distance 100% Missing two U wires 100% Shi9 U plane up by 0.5 mm 100% Missing three U wires 100% Shi9 U plane up by 0.5 mm 96% Missing one V wires 100% Shi9 G plane down by 0.5 mm Missing two V wires 100% Shi9 V plane up by 0.5 mm 100% Missing three V wires 100% Shi9 V plane up by 0.5 mm Shi9 ~88% Missing one U and one V wires 100% U plane down by 0.5 mm Missing one X plane wire 100% Missing two X plane wires ~95% Missing three X plane wires ~80% • If the wire plane gap distance can Missing four X plane wires ~70% be controlled within 0.5 mm, the impact to transparency condition should be small • Missing more than one continuous collection plane wires leads to significant • Requirement: control the wire plane impact on the transparency condition, less gap distance to below 0.5 mm impact for missing induction plane wires 18

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 on 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 19