Preparation for E Pi0 Collaboration Meeting Tuesday Feb R.Lindgren

BigBite and Wire Chambers

Hardware in Hall A Hadron Stack Daq Weldment Electronics VME Rack Ribbon Cables Bertha Power Supply Dollies for cables Rest of cables Bigite? Wire Chambers?

Install cm x 2 cm x 70 cm paddles on VDC to cover -5 to 30 MeV in Delta W. Bogdan and Bryan R- HRS "clamshell flange" (In the Shop) –Use standard window L- HRS "Flange and Snout" to displace air ( Ed Folts) Flangle (Joyce) –being fabricated now, ready by end of month Sieve-slit (Joyce completed design and drawings signed) Tungsten plate -- on site? –Drill holes- design complete insertion mechanism finalized surrounded by a balloon to contain helium Ordered in. Titanium foil for vacuum window?

BigBite shielding "hut" (Macon) –out for bid, no ETA yet –Macon working on where to drill into BigBite magnet to support the "waist shields". Did the 4 4'x8'x1" steel plates for the hut get ordered? Miscellaneous items/questions: hadron stack "foot" pieces (Kanya parts that raise the stack to the right height on the BigBite stand) are on-site (in testlab) BigBite field clamp ready to go? Any modifications to the BigBite support stand needed for the pi0 run? Any shielding inside the BB magnet (ie. above/below the pole-faces) Remote control of thresholds on scintillators

- pi0 target end-cap collimators (designed by Dave Meekins, Lindgren) pi0 helium bag (Lindgren) – on site BigBite bag – on site Chamber bag Bubbler,Tubing, and Gauge Helium supply and vent to outside. Scripts for data analysis (Mitra, David Hamilton) Trigger and prescaling for paddles (See comments by Bob Michaels, Bryan) Data Acquisition Analyer

Singles Rates L= 1 x Hz/cm 2 HRS Electron ~ Rate determined by elastic radiative tail BigBite MWDC Rate ~ Protons ~5 MHz above 30 MeV ~Pions 3 MHz above 100 MeV ~Gammas 50 MHz Scintillator Rates per PMT ~ 200 KHz   Rate in Hz from MAID Rad tail rate in Hz/MeV

BigBite

Signal/Noise vrs Threshold S/N ~2/1  W=1 MeV S/N~80/1  W=20 MeV Signal ~   rate Noise ~ Accidental Coincidence Rate

HRS=12.5 Deg and BigBite =48 Deg Cos (   p ) vs  W(GeV)  p vs Q 2

HRS=12.5 Deg and BigBite=42 Deg Cos (   p ) vs  W(GeV)  p vs Q 2

W=3-4 MeV with BigBite =48 and HRS= Deg 42 Deg Cos (   p )

HRS=12.5 Deg, BigBite=54 Deg Cos (   p ) vs  W(GeV)  p vs Q 2

Cos cm vs Delta W and Q2 vs BB, HRS=20.5, BB=48 Deg

Front Chamber W = MeV, BB=48 Deg, HRS=12.5 Deg y positionx position Proton angle

W=0-20 MeV, BB=48 Deg, HRS=12.5 tof = ns

BigBite = 54 Deg BigBite = 48 DegBigBite = 42 Deg  W vs  HRS=12.5 Deg  W (GeV) Phi

HRS =20.5 Deg  W vs   W (GeV)  BigBite= 42 Deg. BigBite = 48 Deg BigBite = 54 Deg

HRS=20.5 Deg  W vs cos(  *)  W(GeV) cos (  *) BigBite = 42 Deg BigBite = 48 Deg BigBite = 54 Deg

Commissioning Plan (7 Days Use elastic scattering in HRS on Ta and H (CH2 or liquid target?) to check beam energy. Move HRS at 12.5 deg. Consider reducing aperature of HRS by using normal remote controlled HRS collimator if rate is too high in HRS but not in BigBite. Use Carbon foils optics target to check HRS vertex reconstruction along target. Start out at 12.5 Deg. Use hydrogen elastic scattering to check coincident protons in BigBite. Change HRS-L to about 35.4 Deg(?). Set BigBite to 48 Deg. This works for P = 776 MeV/c protons. Also check using radiative tail. Normalize flight paths for TOF measurements of momentum of proton. by sweeping elastic across paddles using TOF Sweep elastic across paddles. Need CH2 solid target. Not much out of plane.

Continued  Need to set discriminators on all scintillators and check electronics. Use same elastic scattering settings as above. We probably need a lower proton energy.  Use sieve slit with above elastic kinematics to check in-plane angle for wire chambers.  Need program to calibrate BigBite Measure beam polarization using Moller polarimeter Calibrate BCM Calibrate BPM Raster Check Beam position with spot ++

Continued  Out of plane angle theta and phi and momentum acceptance checks. Use D(e,e’p) at threshold kinematics with Sieve Slit. Move HRS to 12.5 Deg and BigBite to 48. Deg. (0.4 cm diameter holes) P p = 249 MeV –E=1200 MeV,  e =11.5 deg,  p = deg, q 2 =-0.056, E ’ = MeV –W=1900 MeV, q = MeV/c,, –Rate in HRS = 8214 Hz/MeV, Coinc Rate in BB is 65 Hz/MeV –(Need to account for hole size) –P p = 488 MeV/c –E=1200 MeV,  e = 12.1,  p = deg, q 2 =-0.056, E ’ = MeV –W=2000 MeV, q = MeV/c, –Rate in HRS = 821 Hz/MeV, Coinc Rate in BB is 6.5 Hz/MeV –(Need to account for hole size) –Used Arenhovel calculations to estimate rate.