Acceptance studies & plans for muon shield optimisation Oliver - - PowerPoint PPT Presentation

Acceptance studies & plans for muon shield optimisation

Oliver Lantwin

[oliver.lantwin@cern.ch]

8th SHiP Collaboration Meeting 13th June 2016

Acceptance studies Muon shield optimisation

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting 2/16

Acceptance studies Muon shield optimisation

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 2/16

Aim of these studies

◮ How much do we gain by...

◮ ... improving the muon shield? ◮ ... using a conical vessel? ◮ ... using a longer vessel?

◮ Acceptance studies for hnl (other channels to be added once in FairShip) ◮ Automate this where possible and add to FairShip once ready

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 3/16

Experimental Configuration

◮ Stripped down to the bare minimum: straw tracker, production point ◮ To generate all configurations studied:

◮ Move production point to set distance of tracker from target ◮ Move/redefine front of vessel to adjust length of vessel Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 4/16

Experimental Configuration

◮ Stripped down to the bare minimum: straw tracker, production point ◮ To generate all configurations studied:

◮ Move production point to set distance of tracker from target ◮ Move/redefine front of vessel to adjust length of vessel Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 4/16

Signal production

◮ Produce 100 000 hnl per tracker position from charm+cascade and

beauty+cascade using standard FairShip code → other signal models + decay channels simple to check once implemented in FairShip

◮ Productions used to generate hnl events:

◮ beauty: /eos/ship/data/Beauty/Cascade1M-Beauty.root ◮ charm: /eos/ship/data/Charm/Cascade-parp16-MSTP82-1-

MSEL4-ntuple_prod_18M.root

◮ Default FairShip hnl couplings: U 2

e : U 2 µ : U 2 τ = 1 : 16 : 4.2, normal hierarchy

◮ N2 → µπ only considered here ◮ Studied hnl masses 1,1.6,2,3 GeV, results for 1.6 GeV unless specified otherwise ◮ Pythia simulates hnl in range 0–300m from production point

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 5/16

Signal production

◮ Produce 100 000 hnl per tracker position from charm+cascade and

beauty+cascade using standard FairShip code → other signal models + decay channels simple to check once implemented in FairShip

◮ Productions used to generate hnl events:

◮ beauty: /eos/ship/data/Beauty/Cascade1M-Beauty.root ◮ charm: /eos/ship/data/Charm/Cascade-parp16-MSTP82-1-

MSEL4-ntuple_prod_18M.root

◮ Default FairShip hnl couplings: U 2

e : U 2 µ : U 2 τ = 1 : 16 : 4.2, normal hierarchy

◮ N2 → µπ only considered here ◮ Studied hnl masses 1,1.6,2,3 GeV, results for 1.6 GeV unless specified otherwise ◮ Pythia simulates hnl in range 0–300m from production point

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 5/16

Reconstruction/Selection

◮ Use ShipReco.py minus PID code (use mc truth) ◮ Select any reconstructed1 vertex in the defined vessel volume ◮ Vessel volume is an elliptic cylinder defined by the tracker dimensions and a set

length

◮ O(few 1000) reconstructed events per tracker position ◮ Weight events by lifetime decay probability, normalise by number of generated

events

1reconstructed = both decay products of N2 → µπ in tracker Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 6/16

Selection & vessel geometry

30 40 50 60 70 80 90 Distance from target[m] 6 4 2 2 4 6 y[m]

Accepted decay Vertices

◮ Elliptic-cylindrical vessel dictated by selection, but effectively all reconstructed

events lie in a cone within the cylinder

◮ Vessel length here: ~40m, distance from target: ~40m

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 7/16

Results: Behaviour for vessel distance from target

20 40 60 80 100 120 140

Distance of vessel from target (m)

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Weighted total of selected N2 →µπ

1e 4

Beauty+Cascade Charm+Cascade

◮ Moving vessel closer for fixed vessel length always better (as expected) ◮ Different slope for beauty and charm production ◮ Note: Arbitrary relative normalisation of beauty and charm production

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 8/16

Magnet configurations used for comparison

Technical proposal (tp) design

20 40 60 80 100 120 140

Distance of vessel from target (m)

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Weighted total of selected N2 →µπ

1e 4

Beauty+Cascade Charm+Cascade

Vessel ~60m from target

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 9/16

Magnet configurations used for comparison

New benchmark muon shield? (See Hans’s talk)

20 40 60 80 100 120 140

Distance of vessel from target (m)

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

Weighted total of selected N2→µπ

1e 4

Beauty+Cascade Charm+Cascade

Vessel ~35m from target2 Note: Tracker dimensions the same for all configurations → not the same as in Hans’s 2d simulation

2While fulfilling stricter requirements than TP muon shield: no µ with p > 1GeV in T4 Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 10/16

Results: Hans’s new benchmark vs. tp

Comparing length at fixed vessel distance from target3:

20 40 60 80 100 120 140

Length of Vessel (m)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

Weighted total of selected N2→µπ

1e 4 TP working point distance = 34.0m distance = 59.0m B, distance = 34.0m B, distance = 59.0m

◮ Gain of ~20–40%, depending on production ◮ Optimal length in both cases ~45m

3Uncertainties are scaled Poisson sampling uncertainty. Lifetime weights taken to be exact. Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 11/16

Results: Heavier/lighter hnl

20 40 60 80 100 120 140

Length of Vessel (m)

1 2 3 4 5 6 7

Weighted total of selected N2→µπ

1e 6 B,m=1GeV B,m=1GeV

◮ Little difference for masses 1,2,3 GeV ◮ Similar gain, slightly different optimal lengths between ~40–50m

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 12/16

Results: Heavier/lighter hnl

20 40 60 80 100 120 140

Length of Vessel (m)

0.0 0.5 1.0 1.5 2.0 2.5

Weighted total of selected N2→µπ

1e 4 B,m=2GeV B,m=2GeV

◮ Little difference for masses 1,2,3 GeV ◮ Similar gain, slightly different optimal lengths between ~40–50m

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 12/16

Results: Heavier/lighter hnl

20 40 60 80 100 120 140

Length of Vessel (m)

0.0 0.5 1.0 1.5 2.0

Weighted total of selected N2→µπ

1e 3 B,m=3GeV B,m=3GeV

◮ Little difference for masses 1,2,3 GeV ◮ Similar gain, slightly different optimal lengths between ~40–50m

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 12/16

Conclusions

◮ Moving from 60 → 35m gives us roughly +30% hnl ◮ Consistent with Hans’s rule of thumb of 1% more hnl/m ◮ Optimal vessel length ~45m, approximately independent of distance

→ savings from muon shield also affect overall length

◮ Conclusion true for both production mechanisms

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 13/16

Remaining work

◮ Hope this tool is useful for discussion at this meeting ◮ Integration into FairShip will follow4, implementation details at a SHiP

Software meeting soon.

◮ Implementation problems to solve:

◮ Storage (eos?) ◮ Computing target (lxbatch ? Skygrid?)

◮ Make this standard tool to study vessel shapes for different signals ◮ Other optimal layouts for different channels?

4If you have opinions on how it should be done, talk to me Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Acceptance studies 14/16

Acceptance studies Muon shield optimisation

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Muon shield optimisation 14/16

Status

◮ 2d optimisation has given us feasible benchmark to aim for (see Hans’s talk) ◮ Need full 3d optimisation to be sure, maybe even improvement over 2d ◮ RAL and CERN engineers investigating possibility of B-fields in target

area/hadron stoppers: looks like it’s not impossible, need to wait for details (see Mitesh’s and Victoria’s talks)

◮ In contact with Yandex, will need to/can use their computing clusters for 3d

• ptimisation

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Muon shield optimisation 15/16

Plans

◮ Aiming to run on Yandex Skygrid starting end July

→ get conventional 3d optimisation ready by then

◮ Build on Iaroslava’s magnet design code ◮ Magnet configurations studied will focus on conventional magnets + different

parts of target area magnetised (target itself, hadron stoppers)

◮ ντ -magnet integration? Could investigate as an option, if there is interest. Will

need to think about whether idea feasible, how to implement

◮ I will be moving to cern beginning of July, so expect progress to accelerate then.

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Muon shield optimisation 16/16

[Backup Slides]

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Backup 17/16

Comparison of magnets: tracker position instead of length

60 80 100 120 140 160 180

Tracker distance from Target (m)

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

Weighted total of selected N2→µπ

1e 4 distance = 34.0m distance = 59.0m B, distance = 34.0m B, Vessel distance = 59.0m TP working point Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Backup 18/16

Move vessel front for fixed tracker position

20 40 60 80 100 120

Distance from production (m)

0.2 0.4 0.6 0.8 1.0 1.2 1.4

Weighted total of selected N2→µπ

1e 4

tracker distance = 120m

Oliver Lantwin (Imperial College London) 8th SHiP Collaboration Meeting Backup 19/16