Machine-Detector Interface (MDI) report Presented by M. Weaver, SLAC Operational issues radiation aborts radiation-dose and background monitoring Background characterization characterization experiments long-term projections & vulnerabilities Simulations G4 development status
Presented by M. Weaver, SLAC
<stable-beam trips> ~ 1.7/day (Sep 03-Jul 04)
<injection trips> ~ 0.6/day, 1-31 Jul 04
Since 1 March 04
HER trickle starts
HER trickle starts
increase probably instrumental
Vacuum valve ROD
LER injection-quality monitor
HER injection-quality monitor
Monitor using injection-gated triggers (1 ms x 15 ms)
Injection- & trickle- background history
EMC trigs (always on) LER trickle
DCH trigs LER trickle
EMC trigs (always on) HER trickle
DCH trigs HER trickle
DCH current normalized to Jan 04 background data
SVT ocp’cy @ f = 0 (LEB-sensitive)
DCH L1 rate
Data: Jan 04 (bef. therrmal outgassing crisis)Background characterization measurements
Step 1: Beam-current scans
Step 2: L & beam-beam terms
EMC cluster multiplicity
SVT occupancy (FL1 M01-f)
I outgassing crisis)DCH =DCH
Step 3: Background Parametrizations
Step 4: Background Extrapolations
Tracking efficiency drops by roughly 1% per 3% occupancy
PEP-II parameter projections
LER contribution very small
When combined, higher trigger rates and long read-out time leads to unacceptable deadtime, driven by the DCH
Backward: outgassing crisis)
Background strongly - dependent
By 2007 predict 80% chip occupancy right in MID-plane
In layer 1, 10% will be above 20% occupancy
Integrated dose will be more than 1 Mrad/year by 2007SVT
Background now is ~75% HEB [LEB negligible (!)]
In 2007, it will be 50% HER, 50% L
B Petersen N. Barlow M. Cristinziani/T. Glanzman J. Malcles
Evolution of HER single-beam background, 2002-04
Regularly activating NEGs & TSPs does help !
We should continue to take advantage of single beam opportunities to monitor the background.
10 M. Cristinziani/T. Glanzman J. Malcles9 GeV/s @ L = 1034
P. Roudeau, A. Stocchi, W.K. (preliminary)
Turtle Simulation :
e+ e- e+e-g Background
- z (m)
E M. Cristinziani/T. Glanzman J. Malcles
Electromagnetic shower debris or…
EMC default digi map: luminosity background (N. Barlow)
Neutron M. Cristinziani/T. Glanzman J. Malcless
Measurements appear consistent with Turtle radiative Bhabha simulation + GDR cross sections. Projected neutron rates may affect detector electronics – depends upon neutron energy spectrum.
Turtle Level Simulations M. Cristinziani/T. Glanzman J. Malcles
Beam-gas background from the HER (and LER)
Where do scattered e-come from ?
Where do scattered e-hit?
B1 M. Cristinziani/T. Glanzman J. Malcles
Beam-Beam Collimation Study M. Cristinziani/T. Glanzman J. MalclesLarge X-Emittance: Phase Space Plot
Starting x, x’ coordinates of particles lost along the beamline.
Z location where particles are lost. Colors correspond to upper plot.
+25.2 m from IP M. Cristinziani/T. Glanzman J. Malcles
-25.2 m from IP
Results are based on an older LER deck (’98) with a tune of 0.57 (in x).
Large-amplitude, horizontal b-tron tails originating at the IP can be effectively curtailed at + 25 m
...at least in the simulation
basically because of the phase-advance relationships reduce this to a one-turn problem, and assuming the impact on LEB lifetime remains manageable.
This study should be redone with the new LER deck & current x-tune of 0.51.
Vertical tails are not an issue (in the LER)
Pre-trickle collimator-scan data remain to be analyzed.
However, the +25 m collimator
can’t replace existing PR04 collimators in some corners of phase space
provides no protection against Coulomb scatters between PR04 and PR02
Both horizontal and vertical b-tron tails will be studied for the HERBeam-beam collimation study: summary
Outgassing storms IP can be effectively curtailed at + 25 m
Continued BaBar involvement in IP can be effectively curtailed at + 25 mAccelerator Performance Improvements (I)
BaBar involvement in IP can be effectively curtailed at + 25 mAccelerator Performance Improvements (II)