Beam based calibration for beam position monitor

Transcription

1 TBLA0 Bem bsed clbrton for bem poston montor 5-SEP-05 IBIC05 Melbourne M. Tejm KEK

2 Contents Clbrton t the bennn Includn mppn of BPM hed lnment nd n clbrton of electrc crcut. Bem bsed lnment BBA n net er bem commssonn of KEKB. Bem bsed n clbrton Gn clbrton of BPM n the KEKB We hve done BBGC n ever - month snce 00. New method for n clbrton of BPM n the J-PAC Totl lest squres method s ppled n J-PAC Hh-precson BPM sstem Montorn the consstenc error nd ppln the bem-bsed n clbrton

3 Clbrton of BPM Sstemtc errors n BPM Settn error of BPM to Q-m. Mesurement of Δ? Δ? Offset error Imblnce error n -outputs BPM model elton mon when the bem loctes n the center Gn error the output snls trvel throuh seprte cbles connectors ttenutors nd swtches

4 STEP Mppn of BPM hed All BPMs were mpped t test bench wth movble ntenn. Test bench for the mppn result for mppn HE LE

5 STEP Alnment of BPM heds nst to the Q-mnets Mesurement of the mechncl offsets of the BPM heds to the Q-mnets. Photorph of Mesurement tool esults of lnment of BPM heds nst to the reference plne of the Q-Mnets

6 STEP- Gn clbrton of the electroncs Attenuton of cble swtch electroncs etc. We mesured the dstrbuton of snl ttenuton of the ll electroncs We used dumm hed nsted of BPM heds. esults for rton between output snl BC nd nst to A n ll electroncs A B C Output snls: A B C

7 Bem bsed clbrton Bem Bsed Alnment Mesurement of the offset of BPM to the feld center of the djcent Q-mnet usn the bem. Bem Bsed Gn Clbrton Clbrton of the n mblnce mon four outputs of BPM usn the bem.

8 Bem bsed lnment(bba) - Prncpl - BBA s serchn the bem orbt whch s nsenstve to the chne of feld strenth of Q-mnet. Ths orbt must pssn throuh the mnetc center of Q-mnet. The mesured bem poston for ths orbt s correspondn to offset orn of BPM. Δm0 then δm offset

9 Actul procedure for BBA Bump orbts: [mm] I Q : [A] -current of correcton col from fure ()(b)(c) Δ/ΔI Q nd (I Q 0) where m Δ / Δ I 0 Q Offset 0.9[mm] The orbtl chne due to ΔI Q cn be montored not onl the BPM but b n other BPMs n the rn.

10 strbuton of offsets wth BBA n J-PAC M

11 strbutons of offsets wth BBA In KEKB

12 The BPM offsets mesured b BBA were set n the dt bse for BPM sstem

13 The effect of BBA correcton n J-Prc M Improvement CO wthout / wth the BBA offset dt (red / blue lnes)

14 The effect of BBA correcton n KEKB M

15 Bem Bsed Gn Clbrton BPM wth four button The reltve n of the output dt m drft due to unpredctble mblnce mon output snls from the pckup electrodes. The output snls() must trvel throuh seprte pths such s feed-throuh cbles connectors ttenutors swtches nd then re mesured b the snl detectors. The most probble source of the n drft s the chne n the electrcl chrcterstcs of the trnsmsson lne of the snl b temperture fluctuton. Such s reson the clbrton of the ns of ever BPMs re need.

16 Gn concepton of BPM model

17 The output volte model ( ) for bem bsed clbrton ( ) q F -th electrode () (): bem poston q: proportonl fctor to the bem current : reltve n fctor F (): response functon normlzed to F (00)

18 esponse functon of outputs ( ) ( ) ( ) ( ) ( ) ( ) ( ) 6 b b b b F ( ) ( ) ( ) ( ) ( ) ( ) F F F F F F These coeffcents ( ) (b b ) were determned b fttn the clculted mppn b the fnte boundr element method.

19 Bem mppn & Gn nlss Mesurement of m tmes bem postons b chnn bem orbt. J j j m m ( ) [ ( )] j q j F j j j j ( ) q F Anlss b non-lner lest squre method ( q q ) j j m m m fttn prmeters but / / / To mnmze the sum of the squres of resduls. the softwre technque s Mrqurdt method.

20 Mppn dt b steern mnets for the n clbrton LE_QCP HE_QCE 0 [mm] [mm] [mm] [mm] m5

21 esult of clbrton n KEKB These dt re frst mesurements b bem bsed n clbrton LE HE / / / BPM No. BPM No. The BPM ns mesured b BBGC were lso set n the dt bse for BPM sstem

22 Correlton n the offset between BBA nd BBGC offset offset / K / / K / / / / / / / / / offset K offset K K s coeffcent to poston We converted the mesured vlue of BPM n nto BPM offset vlue nd tred to compre the offset wth the offset from BBA.

23 Correlton n the offset between BBA nd BBGC offset K offset K Some prt of BBA s cused b n drft.

24 BPM hed wth donl cut n J-PAC M The horzontl nd vertcl bem postons re ndependentl detected b two prs of pckup

25 Output of donl cut electrodes L λ λ λ λ λ: proportonl fctor to bem current : rdus of donl cut clnder : reltve n to the L : bem poston B elmnte λ nd L

26 Epresson of m tmes mesurement A b m m m j j A m L j L L b Mtr representton L

27 Wht LS & TLS ( ) Δ m L r ( ) Δ m L d G ( ) G Norml vector to the plne n ( L ) spce epressed s 0 L hve no error L hve error eference:i. Mrkovsk nd S.. Huffel Snl Processn 87

28 Lner lest squres Lest squres Put the A T to both sdes LS A T A A Put the [A T A] - to both sdes [ ] [ ] T A A T T T A A A A A b T b ( T ) T A A A b A hve no error b hve error TLS Totl lest squres A T A A σ : the smllest snulr vlue of [Ab] I: unt mtr T b [ ] T T A A σ I A b Put the [A T A-σ I] - to both sdes [( ) ] T T A A I A b σ A T : trnsposed mtr of A A nd b hve error

29 Smulton of LS & TLS For the smulton The ns set L λ λ λ λ 555 postons wth 0.% Gusssn nose. >500 ponts Smulton result True LS TLS econstruted mppn dt. Blck s Poston() wthout correcton ed s () wth TLS correcton TLS method ndcte d ood reproducblt of ns

30 Bem test Output dt n nne dsplcements of bem postons t BPM. econstructed mppn dt. ed: ( ) wthout correcton Blck: ( ) wth TLS ns Δ 0.5% BPM00 L TLS LS BPM00 L G TLS LS fference n the reltve ns between LS nd TLS

31 esult of the reltve ns of ll BPMs n J-Prc M Kck nles of the steern mnets To obtn the dt wth mpped bem postons Blue: Low ntenst s 0 [PPP] ed: Hh ntenst s 0 [PPP]

32 Evluton of n correcton buttons pckups t the KEKB Bem poston clculton from the outputs ( ) ( ) F F ( ) F ( ) b b b b b b b b b b F Normlzton rd order polnomnls The coeffcents ( n b n ) re obtned b fttn of the mppn dt.

33 Four Postons b selected outputs ( ) ( ) ( ) ( ) ) ( ) ( ) ( ) ( ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) F F F F F F F F AB AB AC AC BC BC ABC ABC ( ) ( ) ( ) ( ) wth wth σ σ The bem poston s lso obtnble from the output volte of n three electrodes chosen out of four electrodes. Normlzton rd order polnomnls If the four outputs hve del correlton (( ) ( ) ( ) ( )) should concde wth ech other. Consstenc error

34 Consstenc error n LE t KEKB Cons.Err.() Before n clbrton Cons.Err.() Cons.Err.() After n clbrton Cons.Err.() The consstenc error becme ver smll

35 Four postons of donl cut pckups t J-PAC L L L L L L L ( ) ( ) ( ) ( ) wth wth σ σ Consstenc error

36 Consstenc error of the bem test t J-PAC Before After [mm] [mm] [mm] [mm] BPM BPM Consstenc error before nd fter n clbrton of BPMs t J-PAC M

37 Conclusons We should p specl ttenton to urntee the precse mesurement of bem postons over lon tme. The BBA clbrton s necessr for correcton of the BPM offset error. The BBGC s lso mportnt for correcton of the mblnced ns mon four outputs of BPM. We hve relzed hh-precson BPM sstem b montorn the consstenc error nd ppln the bem-bsed n clbrton

38 Thnk ou for our ttenton

39 Append