τ appearance optimization -...

Letizia ParatoFinal presentation23 September 2016

ντ appearance optimization

•  DUNE experiment design–  Target hall–  Magnetic horns–  Different targets

•  ντ physics•  ντ appearance optimization

–  Target and the second horn placement•  νμ fluxes

–  Second horn rescale–  Target optimization

•  Work left to do toward optimization•  Conclusions

Outline

9/23/16 Letizia Parato | Final presentation2

DUNE experiment


DUNE experiment design


Target hall

TargethallinreferencedesignwithtwoNuMIhorns

Threehornsfortheop7mizeddesign

(be<erforlowenergyexperiments)

beam



Magnetic hornsPARABOLICHORN•  Focusesagivenmomentumforallpossibleanglesof

entryintothehorn.•  Foragivenshapeandcurrentthefocallengthofthe

hornispropor7onaltothepar7clemomentum.•  Highenergypar7clescouldbeunderfocused(notfully

strengthen)whilelowenergypar7clescouldbeoverfocused.

NuMItarget47graphitetargetsegments,each2cmlongandspaced0.2mmapart,10mminwidth



Different targets

Mul7spherestargetHeliumcooledsphericalarray

CylindricaltargetHeliumcooledgraphiterod

Inthetheoryofoscilla7onsflavourstatesaresuperposi7onsofmasseigenstateswhereα=e,μ,τ.Herethecomputa7onoftheoscilla7onprobabilityismadebyOscProbability.CimplementedintheLBNFcode.Parametersareupdatedto2016andthedistanceatwhichoscilla7onsareobservedis1294km(DUNEfardetector).

ντ physics


Neutrino oscillation probability

Energy (GeV) 0 2 4 6 8 10

Oscil

lation

prob

abilit

y

00.10.20.30.40.50.60.70.80.9

1 = 0CPδ

/2π = -CPδ probabilityµν → µν

Energy (GeV) 0 2 4 6 8 10

Oscil

lation

prob

abilit

y

00.05

0.10.150.2

0.250.3

0.350.4

0.450.5

= 0CPδ/2π = -CPδ

probabilityeν → µν

Energy (GeV) 0 2 4 6 8 10

Oscil

lation

prob

abilit

y

00.10.20.30.40.50.60.70.80.9

1 = 0CPδ

/2π = -CPδ

probabilityτν → µν

ντ physics


ντ : why, how and what we already know

WHYTotesttheunitarietyofPNMSmatrix.HOW•  ντareonlydis7nguishableinCCinterac7ons,whentheyproduceataulepton.

Sincetauisheavy,neutrinoshouldhaveaminimumenergyof3.5GeVtointeractwiththedetector.

•  Highenergypionsareneededtoproducehighenergyneutrinos.•  Isnecessarytomovethetargetfarfromhorn1tocutlowenergyneutrinos

outofthebeamandtoimprovethefocusingsystem.WHATWEKNOWNottoomuch…5eventsfromOpera(fromoscilla7ons)and12fromDONUT(fromDsdecay)

ντ physics


ντ appearance probability at DUNE far detector

Energy (GeV)0 5 10 15 20 25 30

Prob

abilit

y

00.10.20.30.40.50.60.70.80.9

1 oscillation probabilityτν → µν

Energy (GeV)0 5 10 15 20 25 30

)2 (c

mC

Cσ

0

2

4

6

8

10

12 CC cross sectionτν

Energy (GeV)0 5 10 15 20 25 30

)2 x

osc

. pro

babi

lity

(cm

CC

σ 0

0.05

0.1

0.15

0.2

0.25

0.3 CC appearance probability at FDτν

Crosssec7onevaluatedbyGENIEincludedintheLBNFcode



Reference vs. optimized designOp7mizeddesign128ντCCeventsatFDper40ktonperyearStandarddevia7on=8Meanerror=1

Referencedesign225ντCCeventsatFDper40ktonperyearStandarddevia7on=55Meanerror=3

ντ appearance optimizationReference vs. optimized design



Target and second horn placementSetups for the simulation

§  Buffle not installed§  Shield not installed§  Decay pipe snout not installed§  Horns

o  230 kA currento  1.2 MW

§  Beamo  120 GeV proton momentumo  Beam sigma X = 1.7 mm o  Beam sigma Y = 1.7 mm

§  NuMI target o Graphiteo  Fin width = 10.0 mmo  Target length = 1 m

100 jobs with 100k POT eachfor different distances of the target and of horn 2 from the zero point.

For each set I looked for the number of ντ CC events per year per 40 kton (fiducial LArTPC detector mass)



Target and second horn placement

first-second horn distance (m)6 7 8 9 10 11 12 13 14 15 16 17 18

targ

et-fi

rst h

orn

dist

ance

(cm

)

45

75

105

135

165

195

225

255

285

315

345

375

405

435

465

495

0

100

200

300

400

500

600

700

261 279 302 330 329 366 376 395 412 422 434 440

383 402 418 435 467 479 497 511 526 532 548 559

471 489 508 535 540 561 582 600 617 626 638 645

529 553 565 585 605 614 635 648 664 682 694 697

566 574 592 605 619 638 652 672 677 708 710 724

568 580 599 600 618 633 649 668 677 691 709 725

570 575 580 600 607 614 636 652 670 677 685 707

526 550 568 600 593 603 617 624 634 651 667 680

527 534 546 550 554 579 584 596 612 632 632 653

503 506 516 524 533 541 553 565 578 590 612 614

478 487 488 497 508 510 521 540 542 561 587 584

463 471 470 482 484 503 507 530 519 539 555 565

380 380 382 384 389 392 398 424 426 436 443 453

101 102 103 102 114 105 112 114 112 121 126 126

16 17 17 18 17 17 19 20 19 20 21 21

cc events over target and horns distanceτν



Target and second horn placement

•  Horn2hastobeplacedasfaraspossible(17.5m)

•  Thetargethastobe

placedabout2mfarfromthehorn1beginning.



Target and second horn placementνμ fluxes

Energy (GeV)0 5 10 15 20 25 30

/ PO

T2

s / G

eV /

mµν

Uno

sc

0

5

10

15

20

25

3012−10×

flux - target at 90 cm from zeroµν

Horn 2 at 75 m from zero






Energy (GeV)0 5 10 15 20 25 30

/ PO

T2

s / G

eV /

mµν

Uno

sc

0

5

10

15

20

25

3012−10×

flux - target at 210 cm from zeroµν









Target and second horn placementNeutrino parents: how they contribute to the flux

UnoscνμfluxatFD[targetat2.1m-horn2at17.5mfromhorn1]

•  AlmostallneutrinoscomefromthedecayofPions

•  Kaonscontributetothehighenergytailofthedistribu7on




Oscillated

ντCCEven

ts/Ge

V/k

Ton/P

OT



Second horn rescaleSetups for the simulation

§  Buffle not installed§  Shield not installed§  Decay pipe snout not installed§  Horns

o  230 kA currento  1.2 MW

§  Beamo  120 GeV proton momentumo  Beam sigma = 1.7 mm

§  NuMI target o Graphiteo  Fin width = 10.0 mmo  Target length = 1 m

§  Target 2 m far from zero§  Second horn 17.5 m far from zero



Second horn rescale



Second horn rescale

70% radial scaling 100% longitudinal scalingPROCost less ?CONSMore mechanical stress ?

80% radial scaling120% longitudinal scalingCONSIt would be necessary to move horn 2 at 16.5 m from horn 1 losing flux

Is it better to enlarge horn 2 or to make it smaller?

This configuration will be used for the cylindrical and

spherical target simulations



Target optimization2.0 m long NuMI target

first-second horn distance (m)75 95 115 135 155 175

targ

et-fi

rst h

orn

dist

ance

(cm

)

150

180

210

240

270

300

330

360

390

420

450

0

100

200

300

400

500

600

700

477 508 545 575 601 620

509 545 579 608 633 656

521 548 581 605 634 663

523 546 575 605 633 646

501 523 549 585 601 630

496 502 521 558 579 605

466 476 509 517 547 573

435 454 464 483 508 445

443 476 465 505 521 535

476 485 497 520 548 568

482 482 512 537 553 589

cc events over target and horns distance [2 m target]τν

8.5 % less events respect to the 1 m target configuration



Target optimization

13 m

m d

iam

eter

17 m

m d

iam

eter

CC

per

yea

r per

40

kton

τν

770

780

790

800

810

820

830

840

Beryllium spherical target

target length (cm)100 120 140 160 180 200

CC

per

yea

r per

40

kton

τν

800

805

810

815

820

825

830

835

840

845

Beryllium spherical target13 mm vs. 17 mm diameter [1m long target] 13 mm diameter target – events over target length

Multi sphere Beryllium target



Target optimizationCylindrical simple Graphite target

length (cm)100 120 140 160 180 200

diam

eter

(mm

)

3

3.5

4

4.5

5

5.5

6

650

700

750

800

850

900

950

1000

1050

968 993 1015 1003 1008 1009

929 950 959 977 979 963

899 912 940 923 934 925

874 890 892 902 891 881

849 857 857 854 853 852

845 840 831 829 817 822

812 800 814 797 787 783

Cylindrical Targetντ CC events at FD per 40kton per year over cylindrical target scaling

radius

(mm)



Target optimizationCylindrical simple Graphite target

More realistic 5 mm radius target3 mm radius target

Work left to do toward optimization


τ decay channels and signal reconstructionNeutrino’sflavorcanbedetectedonlyinCCevents.Thefollowingtableshowstheτdecaychannelsthatthedetectorisabletoresolveandtheirrela7vebranchingra7o.

Everydecaychannelhashisownbackgroundwhichhastobeevaluatedinordertoes7matethereconstruc7onefficiency.

Work left to do toward optimization


1.  Try target with lower densityFor example a cylindrical target composed by many little cylinders separates by thin layers of air.

2. Using a genetic algorithm Set parameters near to the ones I found and apply a genetic algorithm to find the very best geometry for the ντ appearance.

3. Estimate reconstruction efficiencySimulate CC events at far detector and evaluate the relevant background for the CC event occurred. Find neutrino energy threshold under whom it is not possible to distinguish the signal from the background.

In LArTPC the reconstruction efficiency can be around 20%;

Conclusions


•  Thesecondhornhastobeplacedasfaraspossiblefromthefirsthorn.•  Thetargethastobeplacedabout2mdistantfromthefirsthorn.•  Thesecondhornhasmorefocusingpowerifradiallyrescaledofabout75%

(andallpropor7onalconfigura7ons).•  Athinnertargetwithlowdensityworksbe<er.•  Athinnertargetcanbemadelongerwithoutreducing(ormaybeincreasing)

thenumberofevents:thisisgoodbecauselongertargetmeanslessenergydepositedintheabsorber.

•  Igotamaximumof880ντCCeventsper40ktonperyearusinga(realis7c)cylindricaltargetwith5mmofradiusand150cmoflength.Thismeansafactorof4respecttothereferencedesignandafactorof8respecttotheop7mizedthreehornsdesign.

•  Alotofworkhass7lltobedoneto•  findthebestgeometry,•  es7matethereconstruc7onefficiency.

IpresentedtheseresultstwicetotheBeamInterfaceGroupduringthegroupmee7ng.

Thank you


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