gamma-ray large area space telescope efficiency studies (draft) michael kuss infn pisa instrument...

Gamma-ray Large Area Gamma-ray Large Area Space TelescopeSpace Telescope

Efficiency Studies (Draft)

Michael Kuss

INFN Pisa

Instrument Analysis Group Meeting

1 April 2005

Instrument Analysis Group Meeting, 1 April 2005 Michael Kuss2

Class EfficiencyClass Efficiency

Class Efficiency is used for efficiency studies:

Efficiency(const TString="tree.root", const TString="eff.root", TString geoFileName="");

~Efficiency() { delete myEvent; delete myTracker; }void Go(int lastEntry=-1);// if Get_3_in_a_row would work on the array of TriggerDiagnostics in the// Header tree, it would be faster. But, currently, this array is in the// order of GTCC/GTRC. This stuff should get extracted from TreeMaker// and here, and go into it's own class.bool Get_3_in_a_row(const int layer) const;void Draw2D(TString plane="all", TCut="", float residualDist=1, float borderWidth=1) const;

void GetEfficiency(const TString plane="all", const TCut="", const float residualDist=1, const float borderWidth=1, const bool draw=false) const;

void DrawEfficiency(TString plane, TCut="", float residualDist=1, float borderWidth=1, bool draw=true) const;

private:void PrintEfficiency(TString plane, float ineff, int hits, int missing) const;


General ProcedureGeneral Procedure

user> source cmt/setup.shuser> rootroot [0] .x compile.Croot [1] Efficiency* eff = new Efficiency(”tree.root”,”eff.root”,”geo.txt”)

… opens tree.root for reading, eff.root for writing, and reads the geometry from geo.root.

root [2] eff->Go()

... reads events from the tree file. Selects events with a single straight track (both in x and y). Extrapolates the track into each plane and saves to a small tree:

• event id • plane name • extrapolated x position of the track • extrapolated y position of the track • the distance to the nearest active area (negative if in active area) • the residual to the nearest cluster (sign is of extrapolated - data)

and saves the small tree in the eff-file.

root [3] eff->Draw2D(...)

root [4] eff->GetEfficiency(...)


selecting tracksselecting tracks

?


Draw2D()Draw2D() of a tower of a tower

eff->Draw2D(“all”,eventId<10000,1,5) of run 306000475

dots: extrapolated positions

green: in active area

red: in inactive area

magenta: in active area close to the edge (here, 5mm)

crosses: missing hits

╬: “real” missing hits (if close to the edge, in gray)

x: “fake” missing hits


Draw2D()Draw2D() of a tower (II) of a tower (II)

#17

#6265

#8315

Why are there so few green dots?

The 3-in-a-row condition!


What are these crosses (I)?What are these crosses (I)?


What are these crosses (II)?What are these crosses (II)?


What are these crosses (III)?What are these crosses (III)?


Draw2D()Draw2D() of a plane of a plane

eff->Draw2D("Y3") of run 306000475


GetEfficiency(“plane”)GetEfficiency(“plane”)

root [8] eff->GetEfficiency("plane")OBJ: TCut CUT Object Plane Ladder Wafer Efficiency Inefficiency Hits Missing hits plane Y0 95.2 % 4.8 % 14278 682 plane X0 99.3 % 0.7 % 14380 106 plane X1 88.7 % 11.3 % 12968 1465 plane Y1 99.9 % 0.1 % 13101 19 plane Y2 99.5 % 0.5 % 12647 67 plane X2 99.8 % 0.2 % 12758 20 plane X3 99.1 % 0.9 % 17982 164 plane Y3 89.4 % 10.6 % 17963 1896 plane Y4 88.2 % 11.8 % 17661 2081 plane X4 99.5 % 0.5 % 17698 82 plane X5 99.7 % 0.3 % 17927 47 plane Y5 99.7 % 0.3 % 17942 58 plane Y6 98.4 % 1.6 % 17898 290 plane X6 99.7 % 0.3 % 17884 49 plane X7 99.9 % 0.1 % 18153 27 plane Y7 99.7 % 0.3 % 18164 50 plane Y8 99.8 % 0.2 % 18648 31… tower 98.8 % 1.2 % 648638 7901


Cuts: the 3-in-a-row-conditionCuts: the 3-in-a-row-condition

Assumption: plane X16 has an efficiency of 90%. I let nature generate 100 events like the one above. I will find:

•90 events like the one above

•0 events with no hit in X16, because with that plane the events wouldn’t trigger

I would deduce an efficiency of 100%

Conclusion: I have to impose a 3-in-a-row condition without using the plane to be studied


Cuts: removing “fake” missing hitsCuts: removing “fake” missing hits

Condition: a missing hit is only a missing hit if also the hit of the other plane of the layer is missing.

•seems to remove tracks of missing hits due to stopped particles

•doesn’t remove too many “real” missing hits. Examples:

o planes A and B with 99%: deduced eff. 99.01%

o planes A and B with 85%: deduced eff. 87.25%

o plane A with 85%, B with 99%: eff(A) 85.15%, eff(B) 99.15%

Acceptable? Anyway, I should improve the algorithm!


Hits vs. Trigger RequestsHits vs. Trigger Requests

First 1000 events of 306000475:

•20 good hit but missing TgrReq: 3, 58, 77, 82, 235, 244, 360, 363, 384, 539, 552, 675, 798, 826, 837, 851, 884, 953, 967, 975

•3 noise hit with missing TgrReq: 406, 448, 951

•2 TgrReq but no hit: 169, 608

•1 strange event: 688

All anomalies come with short ToT

All events are at http://www.pi.infn.it/~kuss/glast/IA/IA20050401/


Good Hit but no Trigger RequestGood Hit but no Trigger Request


Noise Hit but no Trigger Request Noise Hit but no Trigger Request


Trigger Request but no HitTrigger Request but no Hit


Strange EventStrange Event


Attempt of an ExplanationAttempt of an Explanation

gamma-ray large area space telescope efficiency studies (draft) michael kuss infn pisa instrument...

Documents

plane x16

plane x0

plane y1

plane y2

plane x2

plane x3

plane y3

plane y4