W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Machine-Detector Interface  Issues  Machine Backgrounds, Present & Future  BaBar involvement in Accelerator Performance Improvements  Summary W. Kozanecki, CEA-Saclay

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03  The Issues  Backgrounds   operational efficiency (this coming run)  long-term projections (2005 & beyond)  New IR design  background simulations: can BaBar live with predicted levels?  make it all fit (unavoidable hardware changes!) [ this topic likely to g r o w in importance]  Accelerator Performance Improvements  background remediation  beam dynamics  instrumentation  IR geometry, orbits & optics  BaBar-based accelerator diagnostics

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Backgrounds: what has happened so far  Try & revive the ‘Background Group’  Strong (and largely successful) effort at  awareness-raising in BaBar (“work on backgrounds? why?”)  recruiting help  Identified subdetector background contact persons (SBC)  Regular MDI meetings (~ every other week)  Background Workshop: Sep 03  In-depth review of radiation-abort policies: “make BaBar & PEP-II transparent to each other”  Run-4 backgrounds: operational issues, vulnerabilities, long-term projections  Launch the background-simulation effort

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Background Sources I (  )  Synchrotron-radiation X-rays  Power: mostly separation dipoles  Background: mostly HER IP quadrupoles  Duck it if you can! else mask it, but watch out for multiple bounces  Masking very effective: SR backgrounds not a problem in BaBar so far  Cool it well - or else!  Lost-particle backgrounds  Bremsstrahlung: e + gas -> e’ +  (E’ < E) By now, almost exclusively from the last few (tens of) m ==> vacuum!  Coulomb scattering: e + gas -> e’ (E’ = E, but  ) Potentially from the whole ring, depending on limiting apertures and on pressure profile. In practice no longer an issue  Touschek : similar to bremsstrahlung BaBar: neglected so far. Should be checked for very-high current operation.  Luminosity (e + e - => e +’ e -’  )  Elm shower debris (radiation + occupancy) + beam-wall p’s (trigger)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 # Xtls > 10 MeV Single-beam backgrounds EMC vs. I +, I - I DCH vs. I + Two-beam backgrounds % occpcy (> 1 MeV) EMC vs. I (I + = 1100) - L1 trigger rate vs. I- (I + = 1100)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Background Projections Background Projections (based on bgds measured in 2000, then 2002) High-Luminosity Model (JS, PEP-II AP Note 130) combined with (  - I - +  - I - 2 ) + (  + I + +  + I + 2 ) +  L Drift Chamber Bakground Projection (July 2000 characterization)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 SVT Bakground Projection Pain threshold: ∫dose ~ 2 MRad  Horiz. plane: ~ 2 MRad by , then MRd/y  Other : ~ 0.25 MRad by 2004, then ~ 0.1 MRad/y DIRC Bakground Projection Pain threshold: PM rate ~ 200 kHz (dead time ~ 300 kHz, 500 kHz) Note how different the relative contributions are between subdetectors July 2000 characterization

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Recent background history: DCH LER current Luminosity Compare measured DCH background to that expected at the same LER current, HER current & Luminosity, based on the Feb characterization

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Background Sources II (  )  Lost-particle backgrounds  Lost-particle backgrounds (continued)  Beam-beam (?) tails ~ Coulomb-like signature ==> collimation ? ( LER !)  elm shower debris in incoming detector straight (esp. LER?)  ‘steady state’ : DCH, IFR – but also SVT (dose + occupancy)  Spikes & fluctuations  DCH, TRG  Radiation bursts  spikes (“fast aborts”)  trapped events  Injection backgrounds  30-90% of SVT dose  45% of EMC dose (CsI calorimeter)  ~ 50% radiation aborts

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Recent background history: SVT, IFR SVTIFR endcap predicted (2002) measured

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 DCH current steady-state level HER lifetime 400 sec Manual abort Radiation bursts Fast (auto) abort

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Injection Backgrounds (Numbers are in krad, (%) is of dose in stable beams) SVT Radiation dose from January to June 2003

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03  SR + beam gas + “Lumi” (e + e -  e + e -  ) (“traditional”)  not an issue  ’05 w/ present IR geometry (&  * !)  however beam-gas in the LER may become a major contributor to the SVT  integrated dose  occupancy once the LER current is raised significantly  Beam-beam tails (SVT occupancy, DCH spikes, dead-time bursts, IFR currents) a growing limitation (including for BaBar data quality)  Interplay between BaBar radiation-abort strategy, and (primarily)  radiation bursts (spikes/trapped evts) ==> significant source of beam aborts  difficult injection (poor injection efficiency, high backgrounds, repeated aborts) ==> major inefficiencies Backgrounds  operational efficiency (’03-’04) Radiation-abort strategy Radiation bursts Injection backgrounds Beam-beam tails

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Backgrounds: long-term projections I Experimental background extrapolations  2005 (2009) Currently based on 2002 bkgd data. An updated characterization will be carried out once PEP-II stabilizes. BaBar hardware/performance limitations?  2005 (2009) (see W. Wisniewski’s talk)  extrapolation of ‘traditional’ backgrounds (in present geometry) valid  200x ?   *  ==> Coulomb still OK?  can one extrapolate beam-beam backgrounds – at all?  how to take into account evolution of injection losses  any limitations/vulnerabilities in Babar hardware or physics performance?  radiation damage?  operational limitations (power supplies, trigger/dataflow bandwidth,...)  physics performance (tracker occupancy/efficiency/resolution, calorimeter resolution)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 SVT elx threshold problem ? Projected integrated dose in SVT midplane Projected integrated dose in SVT midplane (Basis: 2002 characterization, no beam-beam tails, no injection improvements)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Extrapolated dose rates in the SVT mid-plane (stable beams) 50 mR/s ~ 10% chip occupancy Projected SVT data quality Projected SVT data quality (Basis: 2002 characterization, no beam-beam tails) “BaBar needs to better understand the implications of high beam occupancies”

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Projected DCH currents & data-flow dead time Projected DCH currents & data-flow dead time (Basis: 2002 characterization, no beam-beam tails) remedy under active study

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Backgrounds: long-term projections II Beam-beam ? Lattice mods ? (dynamic aperture) Beam-gas simulations ring: Turtle IR  Geant4 SR simulations (an intrinsic part of the new-IR design)  2 themes...  validate IR upgrade design  make sure that what we install in ’05 does not suffer from built-in flaws... ...at least for those processes we can calculate (SR, beam-gas)  understand / improve backgrounds in present machine ...that are intimately intertwined  validation requires credibility  update “old” simulations to incorporate what we learnt  simulations of present machine/detector configuration better get the ‘right’ answer (when confronted with measurements)... ...if we want to believe predictions for the upgraded IR  improve those backgrounds we canNOT calculate  both for today’s and for tomorrow’s sake!

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03  Background analysis & mitigation [BP, LP, TG: some just starting, but too few...]  Background simulations [RB, MB, GC, SM + SLAC (TF/GB)]  Fast monitoring of machine backgrounds  PEP-II [MW, C’OG, AP, GDF,...]  injection quality (SVT, EMC: dDose /dI b )  time distribution of injection triggers  data quality: occupancies, dead time,... for the stored beams in the ‘trickle’ window  more operator-friendly displays (& controls) of radiation inhibits/aborts BaBar involvement in Accelerator Performance Improvements (I) EMC L1 trigger rate

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03  Beam dynamics  beam-beam simulations [IN (Caltech), YC (Slac ARD)]  beam-beam experiments, monitoring of beam-beam performance  Instrumentation  gated camera in LER & HER [D. D., Slac Exptl Grp C + A. Fisher +...] beam-beam effects (flip-flop, ‘raining buckets’, parasitic crossings) electron-cloud effects  development of an X-ray beam-size monitor for the LER: SLAC + zone-plate approach: J A (Caltech) pin hole approach: JK (LBL), HDS  SVTRAD sensor & electronics upgrade [B P et. al. (Stanford); MB/DK et. al. (Irvine) (initiated & funded by BaBar)]  CsI background sensors [JV, Slac Exptl Grp B]  IR geometry, orbit & optics  IR orbit monitoring & stability, IP & ring orbit feedbacks  on-line monitoring of IP position  PEP-II control system [RB, Slac; GDF, Caltech;..]  on-line monitoring of luminous spot sizes  PEP-II control system [MW (Slac); GDF (Caltech); MB/GR (Nikhef);...] BaBar involvement in Accelerator Performance Improvements (II)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Summary  BaBarians... ...have (re-started) contributing significantly to the machine  “BaBar-based machine diagnostics “ a growing & important effort  But more help is needed, esp. on medium- & long-term issues  BaBar vulnerabilities better understood  short term: SVT elx chip, DCH data flow, IFR aging  medium term: SVT (& EMC ?) integrated dose, tracker occupancies, physics systematics  ?? implications of lattice mods (   dyn. aperture) for backgrounds?  Most urgent short-term gains  injection (lack of reproducibility, abort cascades, ++dose, fatigue)  beam-beam tails (more agressive and/or upgraded collimation)  radiation bursts (“dust events”)  Most significant long-term gain potential  LER vacuum in last 20 m (?) [tbc by updated bgd characterization]  injection (30-90% of integrated dose in SVT & EMC)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Appendix: radiation bursts (aka ‘dust’ events)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03  Statistical study of trapped event properties (T. Schietinger, 1999)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03  SVT diode pattern during trapped events  typical, but not universal

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 An odd sequence of slow radiation bursts (2003) ? ?

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 An odd sequence of slow radiation bursts (c’td) ?

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 A collection of fast radiation spikes (stored beams)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Geometry of some detectors useful for such studies (East)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Radiation bursts: “summary”  Statistical study of trapped event properties (T. Schietinger, 1999)  SVT diode pattern during trapped events  A collection of recent slow & fast radiation bursts  Some guesses...  NEG dust from near IR pumps?  gas ‘bubbles’? (would explain correlation with current increases)  possibly some incorrectly latched fast beam instabilities (RF, TFB ?) ...but certainly no coherent picture nor robust interpretation

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Spare slides

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 PEP-II Mid-Project Evaluation Resources Ewan Paterson, TD Persis Drell, RD Bill Wisniewski, Babar Resources Ewan Paterson, TD Persis Drell, RD Bill Wisniewski, Babar Parameters,  L dt Parameters,  L dt John Seeman, Stan Ecklund Jonathan Dorfan, Co-ordinator Lattice/Model Tor Raubenheimer Uli Wienands Vacuum Systems Nadine Kurita Scott DeBarger RF System Ron Akre Ray Larsen Feedback Systems Eric Colby Dmitry Teytelman Reliability/Uptime Roger Erickson Name #2 Machine/Detector Interface Witold Kozanecki Guy Wormser New IR Design Mike Sullivan Name #2 Diagnostics Mark Ross Steve Smith Injection Franz-Josef Decker Name #2 Controls Tom Himel Rusty Humphrey stricly speaking

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Fast Abort Changes  Will leave abort settings during stable beams unchanged  Forgiveness (2 Rad) cannot be increased as that endangers the SVT  Increasing threshold (~1 R/s) could result in running at >1R/s for 10 minutes, which we do not want to try  We can try to change settings during injection  There is no immediate danger to the SVT as it is not biased  The increase in dose (a few krad/year) would be regained if we can get rid of 10-20% of the aborts  Suggested change: Increase forgiveness by factor 3 over stable beams (e.g. 6-8 rads) Set threshold at 2 times stable beams (~2rad/s) instead of 5 times  Would like to have causes of aborts, which still occur be identified and logged by operators Brian Petersen, 3 Oct 03

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Slow Abort Changes  We will enable “extend” button for 10-minute timer, but restrict it to 10 additional minutes  We will monitor it for abuse (of course)  Activate 10 minute timer for the diamonds  Suggest to replace BW:MID diode with BW diamond  Use threshold of 75 mrad/s? Changes can be implemented by next week Brian Petersen, 3 Oct 03

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Possible Longer Term Changes  Should separate “forgiveness” from protection against very fast spikes  Very quickly abort beams on dose rates of 0.1 to 1krad/s  Allow rates of Rad/s for a little longer (x2-4?) than today  Requires the SVTRAD1.5  Abort only one beam?  Not clear that HER and LER always clearly separated during aborts  Gain in integrated dose will be minimal as most aborts would be of the HER  Would require new electronics in IR-2 alcove (previous electronics were done by Mark Petree) Brian Petersen, 3 Oct 03

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 MID Radiation Doses Until Now Budget is set to reach 4 Mrad by 7/ (to be lowered?) FW:MID is consistently overestimated in Run 3

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 TOP Module Doses until 2009 TOP modules look OK, except if FE:TOP becomes MID module BW:TOP and FW:TOP doses are probably overestimated 85-90% of the dose is supposed to come from injection

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 BABAR scorecard today X: visible effect with non-zero impact - : visible effect with no impact ? : yet unknown fixed: det upgrade to fix a significant issue G. Wormser, Bgd Workshop summary, 24 Sep 03

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 BABAR scorecard July 2004 G. Wormser, Bgd Workshop summary, 24 Sep 03

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 BABAR scorecard July 2006 G. Wormser, Bgd Workshop summary, 24 Sep 03

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 BABAR scorecard 2009 G. Wormser, Bgd Workshop summary, 24 Sep 03

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Architecture of background simulations (1)  Synchrotron Radiation  MAGBENDS / QSRAD: stand-alone programs  SR background calculations: an intrinsic component of IR re-design  shouldn’t these be interfaced to GEANT?  Beam-gas  step 1: LP-TURTLE transports particles around 1 ring turn  full model of ring optics (treated as transport line)  start with ‘nominal’ beam at IP  beam-gas scattering randomly around ring (bremsstrahlung or Coulomb scattering)  transport ‘secondaries’ (e’,  )  simplified model of IR apertures (simple geometry, no showering!)  those particles lost ‘near’ the IP are scoring plane input to step 2  step 2: full GEANT simulation of detector + near-IR ( m)  see Mario Bondioli’s talk

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Architecture of background simulations (2)  Beam-beam  full simulation of beam-beam tails impractical  focus on collimation studies  optimize collimator placement/relocation (SM)  understand main characteristics of collimator secondaries (HB)  provide guidance for machine experiments  use Turtle machinery  Strategy considerations  improve/update description of magnetic fields & apertures (TF, GC)  many fundamental features easier to understand at Turtle level   first round of IR-upgrade design validation will be done this way (RB)  GEANT-level simulation essential (MB, GB, GC)  to benchmark computations against data  to make sure there are no “alligators” hiding in new design  absolute background predictions always suspect  even when benchmarked against experiments. However... ...ratios (new design /present machine) much more reliable.

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Lost-particle backgrounds IP Normalized to: - uniform pressure profile of 1 nT - 1 A beam current IP Coulomb scattering in Arcs (y- plane) e - Brems- strahlung in last 26 m (x-plane) Vacuum pipe / mask apertures

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 The “Background Zones” reflect the combined effect of....  beam-line geometry (e.g. bends)  optics at the source and at the detector distant(good!)  aperture restrictions, both distant (good!) & close-by (bad!) X (mm) Zone 1 X (mm) Zone 2 Zone 3 X (mm) IP Zone 4 Coulomb scattering in Arcs Bremmsstrahlung in field-free region Bremmsstrahlung

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Benchmarking of simulations: comparing “predicted” and measured background levels  Radiation patterns  for a given sensor type: independent of absolute calibration  among different sensors: compare fractional derivatives  Absolute background levels  sensor calibration!  absolute pressure profile !  Global consistency/sanity checks  operational experience in MCC

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Pressure-bump experiment: NEG heating in BaBar straight Vacuum gauge reading (nT) Create localized P-bumps NEG heating DIPS on/off Measure response of background monitors Compare relative measured & simulated monitor response to validate Monte Carlo Different regions ==> diff. patterns diff. abs. levels Abort diode signal (mR/s)

W. KozaneckiPEP-II MAC Review, 9-11 Oct 03 Compare measured & predicted dose rates in HER: Monte Carlo lost-particle simulation (Turtle + BBSIM) validated by p-bump experiments Computed pressure profile in detector straight section (N 2 -equivalent, not vac.-gauge units!) Average ring pressure (from lifetime) for arcs & distant straights Understanding the absolute level of HER backgrounds (Sep 99)