Backgrounds using v7 Mask in 9 Si Layers at a Muon Higgs Factory T. Markiewicz & T. Maruyama / SLAC MAP Detector Group Meeting 8 August 2014

Masks v2 versus v7 8 Aug 2014 - MAP at SLAC T. Markiewicz

Comparison with Striganov (2 bunches, 1 BX) Striganov |Z|<600cm FLUKA |Z|<600 cm FLUKA |Z|<350 cm Striganov |Z|<???  3.2×109 4.0×109 2.1×109 5.6×108 6.7×108 e 1.2×108 1.6×108 8.7×107 3.5×106 4.0×107 n 1.7×108 1.4×108 7.3×107 6.4×107 6.6×107 h 1.0×105 2.0×105 7.7×104 1.7×104 2.5×104 8 Aug 2014 - MAP at SLAC T. Markiewicz Seems anomalous

320um Silicon Conversion/Scoring Planes Barrel Detector Radius (cm) Half Length (cm) VXD 5.5 20.5 Tracker 50.0 91.0 ECAL 131.0 200 Barrel Detector Radius (cm) Half Length (cm) VXD 7.7 28.7 Tracker 50.0 91.0 ECAL 131.0 200 Endcap Z (cm) Rin (cm) Rout (cm) VXD 24.8 6.7 18.4 Tracker 92.0 25.2 53.3 ECAL 200.1 38.0 130.9 Endcap Z (cm) Rin (cm) Rout (cm) VXD 30.0 6.7 18.4 Tracker 92.0 25.2 53.3 ECAL 200.1 38.0 130.9 8 Aug 2014 - MAP at SLAC T. Markiewicz

Pythia timing to set a timing gate for each layer Timing resolution not considered Barrel 1 Barrel 2 Barrel 3 1.5-4ns 4-10ns 0-1ns Time (ns) Z (cm) Endcap 3 Endcap 1 Endcap 2 6.5-9ns 0.5-1.5ns 3-4ns 8 Aug 2014 - MAP at SLAC T. Markiewicz R (cm)

Converted Photons 8 Aug 2014 - MAP at SLAC T. Markiewicz

Time and z of converted photon background All Si Layers X100 to get background associated with one bunch 8 Aug 2014 - MAP at SLAC T. Markiewicz

V7 Hit multiplicity (all layers) nh-1 counts all charged “children” hits of a photon leaving the mask The long tail (cut in GEANT at 200) skews the mean multiplicity What is the correct multiplicity to use? NB: 19759 (γ that conv.) x 200 / 6.7E8 (FLUKA γ) = 0.59% conv. eff. 8 Aug 2014 - MAP at SLAC T. Markiewicz

What is the best way to simulate detector hits? Setup massless scoring plane, score photon crossings and apply fixed conversion efficiency x hit multiplicity(2%). Under estimate spirals. Technique for ILC studies Setup Si layer and massless scoring plane, and score only charged particle crossings. There are very low energy spirals inside the scoring volume . There are low energy electrons that don’t come out of Si. Setup only Si layer and score only energy depositions.  8 Aug 2014 - MAP at SLAC T. Markiewicz

Photon conversion prob. in 320 m Si from EGS Approx. range of gamma energies Edep > 8 keV Edep > 30 keV 8 keV is assumed E_dep to produce a signal on a VXD pad 0.6% is observed eff. LOG10(E(MeV)) LOG10(E(MeV)) 8 Aug 2014 - MAP at SLAC T. Markiewicz

Z Distribution of Photons in Innermost Barrel VXD All hits First hit only Inner VXD: γ Conversion eff: 6581/1,121,001=0.587% Hit Multiplicity = 89207/6581 = 13.555 8 Aug 2014 - MAP at SLAC T. Markiewicz

Innermost VXD Layer Separation between Hits that stay on the layer 20 um bins Adjacent Hits 20 um bins Most probable length of string of hits ~ 1mm Average separation between adjacent hits ~2mm (??) Both >> 20um pixel pitch -> non adjacent pixels will be hit 8 Aug 2014 - MAP at SLAC T. Markiewicz

Numerology for hits on Innermost VXD Layer Set MaxHit=2 Inner VXD: 1,121,001 photons make a hit on this layer There are a total of 89207 hits seen 6581 photons make one or more hits on this & other layers In 5872 cases all the hits stay on this Inner VXD layer; In 709 cases the last hit in the n-tuple is on a different layer 1053 of 6581 (or 5872) events only have one e- hit on the layer In 4819 of 5872 events, all the hits stay on the inner VXD layer When >1 hit, the max. probability of separation between first and last hit is 1mm Conversion eff: 6581/1,121,001=0.587% Hit Multiplicity = 89207/6581 = 13.555 This is ~ 3.1x the mean number of hits when histogram truncated at 20 hits. 8 Aug 2014 - MAP at SLAC T. Markiewicz

Innermost VXD Layer-Converted Photons 34.4% in 0-1ns <>=311; Peak/<>~2 8 Aug 2014 - MAP at SLAC T. Markiewicz

Cut nh-1<20 37% hits left after cut 58.3% in 0-1ns 1.7x as many hits are left after the timing cut 8 Aug 2014 - MAP at SLAC T. Markiewicz

Converted photon hits on r=50cm Barrel 50.8% in 1.5-4ns 82.8% in 1.5-4ns After nh cut <>=301; Peak/<>~2 25% hits left after nh cut 8 Aug 2014 - MAP at SLAC T. Markiewicz

Time Distribution of photon hits on r=131cm Barrel 95.3% in 4-10ns After nh cut 92.3% in 4-10ns <>=131; Peak/<>~2 34% hits left after nh cut 8 Aug 2014 - MAP at SLAC T. Markiewicz

Time Distribution of photon hits on 2 VXD disks at z=25 or 30cm, 6 Time Distribution of photon hits on 2 VXD disks at z=25 or 30cm, 6.7<r<18.4 After nh<21 cut 78.6% in Gate 0.5<t<1.5ns <>=14; Peak/<>~10 97% hits left after nh cut Peak due to inner barrel VXD layer 8 Aug 2014 - MAP at SLAC T. Markiewicz

Time Distribution of photon hits on 2 disks at z=92cm, 25.3<r<53.3cm 67.3% in Gate 3<t<4ns <>=4.4; Peak/<>~5 Peak due to inner barrel tracker layer 8 Aug 2014 - MAP at SLAC T. Markiewicz

Time Distribution of photon hits on 2 disks at z=200cm, 38<r<130 Time Distribution of photon hits on 2 disks at z=200cm, 38<r<130.9cm 59% in Gate 6.5<t<9ns <>=4.2; Peak/<>~6 8 Aug 2014 - MAP at SLAC T. Markiewicz

e- backgrounds Good comparison v2 versus v7 8 Aug 2014 - MAP at SLAC T. Markiewicz

e+e- backgrounds: All scoring planes v7 v2 8 Aug 2014 - MAP at SLAC T. Markiewicz

e+e- backgrounds: All scoring planes v7 v2 8 Aug 2014 - MAP at SLAC T. Markiewicz

Time Distribution of e+e- hits on Innermost Barrel 5.3% time=time_parent+time_child 0-1ns gate v7 v2 <>=162 Peak/<> ~ 5.5 8 Aug 2014 - MAP at SLAC T. Markiewicz

Relatively few e+/e- Backgrounds make it to the r=50cm barrel but those hits are “in time” with physics events v7 v2 v7 v2 8 Aug 2014 - MAP at SLAC T. Markiewicz

Relatively few e+/e- Backgrounds make it to the r=131cm surface of the barrel Ecal, but those hits are “in time” with physics events v7 v2 v7 v2 8 Aug 2014 - MAP at SLAC T. Markiewicz

time=time_parent+time_child Time Distribution of e+e- hits on z=25cm Disks Many, many spirals before hitting disk delays arrival v2 v7 time=time_parent+time_child 0.5-1.5ns gate 1% in 0.5-1.5ns gate v7 <>=113 Peak/<> ~ 4.4 v2 8 Aug 2014 - MAP at SLAC T. Markiewicz

Relatively few e+/e- Backgrounds make it to the z=92cm fwd tracker the tighter time cuts help further as e+/e- source is far up the cone, away from the IP at large z v7 v2 <>=2.5 Peak/<> ~ 4 v2 v7 2% in 3-4ns gate 8 Aug 2014 - MAP at SLAC T. Markiewicz

Relatively few e+/e- Backgrounds make it to the z=200cm surface of the Endcap Ecal the tighter time cuts help further as e+/e- source is far up the cone, away from the IP at large z v7 v2 v2 v7 4% in 6.5-9ns gate 8 Aug 2014 - MAP at SLAC T. Markiewicz

Neutrons 8 Aug 2014 - MAP at SLAC T. Markiewicz

Detector hits simulation for neutrons Setup simple fluka geometry. Score all particles produced inside Si Look at energy deposition per incident neutron. 320 m neutron 8 Aug 2014 - MAP at SLAC T. Markiewicz

 106 25 MeV neutrons p 4He e- Neutron energy d e+ t 3He E (MeV) Particle type 8 Aug 2014 - MAP at SLAC T. Markiewicz

Energy deposition per incident 106 25 MeV neutrons 106 100 MeV neutrons 0.1% 0.07% Energy deposition in Si (MeV) 8 Aug 2014 - MAP at SLAC T. Markiewicz

Neutrons In this simulation, neutrons do not interact with Si in layers but can hit the layer more than 1 time or can hit more than 1 layer 8 Aug 2014 - MAP at SLAC T. Markiewicz

Parent Neutrons Leaving Mask 8 Aug 2014 - MAP at SLAC T. Markiewicz

Z and Time Distribution of all Parent Neutrons Transition to B-CH2 8 Aug 2014 - MAP at SLAC T. Markiewicz

ALL Layers-Children of Parent Neutrons 8 Aug 2014 - MAP at SLAC T. Markiewicz

All Layers--Children of Parent Neutrons Digitization of neutron energy <20MeV in FLUKA Momentum (MeV) 8 Aug 2014 - MAP at SLAC T. Markiewicz

Innermost VXD Layer-Neutrons <>=43; Peak/<>~5 8 Aug 2014 - MAP at SLAC T. Markiewicz

Innermost Tracker Layer at r=50cm Neutrons 6.7E-4 in 1-4ns <>=1287; Peak/<>~2 8 Aug 2014 - MAP at SLAC T. Markiewicz

OuterMost Ecal Layer at r=131cm Neutrons 1.8E-3 in 4-10ns <>=711; Peak/<>~1.7 8 Aug 2014 - MAP at SLAC T. Markiewicz

InnerMost VXD Disk at z=30cm Neutrons 4.3E-4 in 0.5-1.5ns <>=100; Peak/<>~1.2 8 Aug 2014 - MAP at SLAC T. Markiewicz

First Tracker Disk at z=92cm Neutrons <>=105; Peak/<>~1.1 4.7E-4 in 3-4ns 8 Aug 2014 - MAP at SLAC T. Markiewicz

ECAL Disk at z=200cm Neutrons 1.5E-3 in 6.5-9ns <>=72; Peak/<>~1.4 8 Aug 2014 - MAP at SLAC T. Markiewicz

Charged Hadrons 8 Aug 2014 - MAP at SLAC T. Markiewicz

Charged Hadrons 8 Aug 2014 - MAP at SLAC T. Markiewicz

Parent Hadrons Leaving Mask 8 Aug 2014 - MAP at SLAC T. Markiewicz

Z and Time Distribution of all Parent Charged Hadrons 8 Aug 2014 - MAP at SLAC T. Markiewicz

ALL Layers-Children of Parent Charged Hadrons 8 Aug 2014 - MAP at SLAC T. Markiewicz

All Layers--Children of Parent Hadrons 8 Aug 2014 - MAP at SLAC T. Markiewicz

Innermost VXD Layer-Hadrons <>=22; Peak/<>~1.5 8 Aug 2014 - MAP at SLAC T. Markiewicz

Innermost Tracker Layer at r=50cm Charged Hadrons <>=27; Peak/<>~1.5 20% in 1-4ns 8 Aug 2014 - MAP at SLAC T. Markiewicz

OuterMost Ecal Layer at r=131cm Charged Hadrons 36% in 4-10ns <>=6; Peak/<>~1.8 8 Aug 2014 - MAP at SLAC T. Markiewicz

InnerMost VXD Disk at z=30cm Charged Hadrons 16% in 0.5-1.5ns <>=12; Peak/<>~1.3 8 Aug 2014 - MAP at SLAC T. Markiewicz

First Tracker Disk at z=92cm Charged Hadrons 20% in 3-4ns <>=8.3; Peak/<>~1.5 8 Aug 2014 - MAP at SLAC T. Markiewicz

ECAL Disk at z=200cm Charged Hadrons 35% in 6.5-9ns <>=12.9; Peak/<>~2.3 8 Aug 2014 - MAP at SLAC T. Markiewicz

Background Summary 8 Aug 2014 - MAP at SLAC T. Markiewicz

Contributions to Average Hit Density per Read Out Unit per 1000 Bx Before Timing Cuts 8 Aug 2014 - MAP at SLAC T. Markiewicz

Contributions to Average Hit Density per Read Out Unit per 1000Bx After Timing Cuts 8 Aug 2014 - MAP at SLAC T. Markiewicz

Sum of all Background Sources after Timing Cuts Average Background per Silicon Layer Peak/Average Ignored (can be up to x10 for γ in Endcap VXD) 8 Aug 2014 - MAP at SLAC T. Markiewicz

Sum of all Background Sources after Timing Cuts Peak Background per Silicon Layer Ignore density variation in Phi 8 Aug 2014 - MAP at SLAC T. Markiewicz

Conclusions Change to the version 7 conic mask design with larger beampipe radius reduces backgrounds x2-3 We do not see the x30 reduction in the e- channel shown by MARS Irreducible backgrounds in the photon and electron channels emanate from the IP area, predominately from the downbeam cone tip, and are thus largely in time with the collision Nonetheless, timing in tight gates can reduce these backgrounds ~x2 Neutrons and charged hadrons emanate from the body of the conic mask Timing can reduce the charged hadron background by x3-10 The neutrons, which dominate the hit density outside the barrel VXD, are very slow and are very effectively eliminated by timing: only .05-.15% remain after cuts An accurate determination of hit density requires a detailed detector model, ideally with clustering. The simplified model used in this analysis has shown Photon backgrounds convert with 0.6% probability in 320um layers of Silicon While the “most probably” number of hits per converted photon is 2-3, there is a long tail (artificially cut at 200) that drives the mean number of hits to >10. The average separation of these hits is ~1mm, so it seems like they would “count” in the tracking & vertex detectors ILC analyses assumed 2% for the product of conversion probability and hit multiplicity; the analysis here results in ~ 6% As all the neutrons are cut by the timing gate, we habe only SCORED them in this analysis Separate studies indicate that these low energy neutrons will produce visible hits in thin Si 0.1% of the time Signal in calorimetry has not been studied Timing cuts not particularly effective given (in this IR geometry) proximity of cone tips to the IP (±0.7ns away) Silicon strip tracker (50um x 1cm) show 100%-500% occupancy per BX to be compared to ILC performance of 1-2%. Can argue what is max. allowed (10%), but 100% does not work. Hits per readout unit per train (1000 BX) >> 4 buffers designed for the ILC Readout architecture (“KPIX”) Reading each readout element each bunch crossing probably required Barrel backgrounds more important than endcap backgrounds Endcap hits caused by spiraling e+e- are out of time when they hit endcap trackers Tracker backgrounds with 50um x 1cm strips >> VXD backgrounds with 20 um x 20um pixels Barrel and Endcap ECAL need to passively absorb 50-200 ~1 MeV photons/pad/BX without showing a hit 8 Aug 2014 - MAP at SLAC T. Markiewicz