The motivations, discussions, and preliminary conclusions of the LASL Kaon Factory Seminar, which met 15 times in the Spring of 1979, are reported. It is technically feasible, but expensive, to build a kaon factory using LAMPF as an injector. Taking advantage of the increased beam intensity, excellent secondary beam lines could be built. While we continue further study of the physics justification for a kaon factory, we also propose to gradually increase LASL participation in kaon and antiproton physics

Silbar, R.R.

UNT (University of North Texas) Digital Library

LA-UR -79-2137 MASTUTITLE: REPORT ON THE LOS ALAMOS K40N FACTORY SEMINAR: PHYSICSAUTHOR(S): R. R. Silbar, T-5SUBMllTED TO: 8th International Conference on High Enctgy Physicsand Nuclear Struc~uY’e~ August 13-173 ~97~1 VancouverB. C.By acceptance of this ar!lcle, the publisher recognizes that theUS. Governrmn( retmns a nonexclusive, royally free Ilcenseto publ)sh or reproduce the publishpd form of this contrlbu-1, or 10 allow others to do so, for US, Governmel)! ImrsThe Lo: Alamos Sclentlf)c I.,horatory re[~ues!s that the pubIisher Identify this article as work performed under !he ausplces 01 the U.S Departnwnt of Energy.Ls!lliikLOS ALAMOS SCIENTIFIC LABORATORYPost Office 130x1663 Los Alamos, New Mexico 87545An Affirmative Action/Equal Opportuni~ EmpbyefForm No, 836 R3St. No. 262912/70UNITED STATESDEPARTMENT OF ENERGYCONTRACT W-74 QS-ENG 36hI!ASTER.REPORT ON THE LOS ALAMOSKAON FACTORY SPMINAR: PHYSICSRichard R. SilbarTheoretical Division, Los Alamos Scientific LaboratoryLos Alamos, New Mexico 87545J!ESTRACTThe motivations, discussions, and preikinary conclusions of theLASL Kaon Factory Seminar, which met 15 times h the Spring of 1979,are reported. It is technically feasible, but expensive, to build akaon factory using LAMPF as an injector, Taking advantage of theincreased beam intensity, excellent secondary beam lines could bebuilt. While we continue further study of the physics justification.for a kaon factory, we also propose to gradually increase LASL parti-cipation in kaon and antiproton physics.INTRODUCTION“A very important factor if one looks forward to a kaon factory,”Louis Rosen remarked in a Physics Today article In 1966, is that a linac,such as the then-proposed LAMPF, could increase its energy by addingstages of acceleration. In the time since then, we have been buildingand learning how to use UMPF, and this suggestion has lain more orless dormant. This last summer, however, it became clear that thequestion of a kaon factory was now ripe for consideration. This re-sulted in a report to the LAMPF User’s Group Long-F!angePlanningCommittee,lwhich discussed a possible configuration for a kaon factoryextension of LAMPF and the kinds of physics questions that could beaddressed by such a facility. In this report it was suggested that aworking group be formed to study technical and scientific issues inmore detail.In the Fall of 1978 we began discussing formation of such a ~rc~?.We were spurred on in this regard by the realization that people acTRIUMF, our Canadian counterpart, had already presented preliminarydesign studies of a kaon factory extension for TRIUMT at the CyclotronConference in Bloomington, Indiana.z Further, in conversations withV. M. Lobashov (Inst. for Nucl. Res., Moscow), it also became apparentthat our Soviet colleagues in K:eGnaya Pakhra may have intentions ofconverting as soon as possible the meson factory under constructionintc a kaon factory.3 Also, the LAMPF Technical Advisory Panel hadurged the LAMPF management to direct some effcrt to long-range studiesalong this line. Thus, with the encouragement of Rosen and under thegeneral Puidance and prodding of Darragh Nagle (a preliminary olganzza-tional meeting wns held in his office in December), the Kaon FactoryWorking Seminar (KFWS) began its meetings on January 8, 1979.The structure of the KFWS was broken down into two intermeshingsubtopics--the physical aspects (organized by R. R. SiLbar and J. D.Bowman) and machine/facilities aspects (organized by R. J. Macek andA. A. Erowman). LASL divisions participating were Ml?,T, and, to alesser extent, CNC, P, and AT, About ten persons were regularattendees, but up to 20 people were at times present for a particularsession. The seminar met 15 times during the Spring of 1979. In manyresppcto it was a learning experience for most, if not all, of us. T,lelast meeting before a long summer break wfm held in May, but we expectthe KFWS to resume meeting in the fall.In tl.istalk I will briefly summarize the physics aspects of ourdiscussions. You will hear tomorrow from l?arraghNagle more detailconcerning our machine-related and exper~.mental-facility-relatede?.ib-erations. Also, tomorrow afternoon, Peter Herczeg will talk about whatmight be learned from a kuon factory regarding kaon and hyperon decays.This talk is an outgrowth f’L”UD one that Herczeg gave in the KFWS inApril.The subjects I will discuss today will necessarily be treatedsomewhat cursorily’. You should view what I say more “- a report onour seminar’s activities than as an in-depth discussion ef thesephysics topics. In fact, most of these subjects will be dealt with indetail by other speakers in this Hcrl-shopor in the ICOHEPANS program.I will try to flag the connections to these talks when appropriate.Although the kaon factory I am going to talk about would be auser-oriented facility, with user irlputat all levels of policy,❑uch of what I will say has a strong LASL-centric flavor. Should LOSAlamos get involved in proposing a kaon factory? Does it fit in vithour laboratory-wide goals? Is it the ni~turalextension of LAMPF, or issome other direct?on more appropriate for us to pursue? These questionswere always in the back of vur minds as we met.To conclude these introductoryremarks, let me state the majorconclusions of our first half-year of the seminar:1.) It is technically feasible t:obuild a kaon factory u: IgLAFfPFas an injector (see Fig. 1). A reasonable energy for such aproton accelerator would be 15 to 30 GeV with a beam current of 100u amps, some 100 times more intensity tk.n is available at the Brook-haven AGS accelerator. The cost of suc;na &chine, t’~getherwithexperimental areas and facilities, iE crudely estimated to be $150 M.2.) It looks feasible to build tiproved beam lines to take advan-tage of the increase in primary beam intensity. Such beams would haveboth good purity and flux.3.) The largest remaining question is whether the physics so bedone with such a kaon factory is worth the cost and zffort. We believea number of the Important topics of interest have now been identified,but they need critical study. Bear in mind, however, that some ofthe most interesting experimental programs being carried out at mesonfactories today were not dreamed of in the original justification.4.) A kaon factory need not necessarily be built at Los Alamos,but there are certain advantages to doing so. LAMFF can be used as aninjector and there is a resemoir of experience in dealing with thetransport of high-intensity beams and ~’ithhigh-radiation-laveltarget cells. LAMPF itself would continue to be available for pursuitof physics and applications with the 800 MeV beam. At the time thekaon factory would becvme operative, however, many of the physics acti-vities and experimental facilitie:lwould probably be diverted to dealingvith kaons and antiprotons.-------- -.-”- -..-./-” ..‘. ‘.>.t,. . . . ..- . .AON RING ;;..{ :100 pA!l~ !15–30 Gev I’ ‘j %A~t~, ,# ,,, 1;. #’H-.’>.”‘. -.. ..--------- .- .. ... ...- .LINAC} =Ito WNRFig. 1. A theorict’s-eye view of a kaon factory at LAMPF.CHRONOLOGY, SPRING 1979ThC?fiftee~lsessions of the seminar, in summary, covered thefollowing topics.January 8An organizational meeting, led by R. R. Silbar, which includeddiscussion of competing projects at other national laboratories, reviewof previous kaon factory studies and workshops on “kaon physics,” anexample of how increased intensity would help In a “°Ca(@,@)kOCaexperiment, andor discussed inJanuary 15Remarks bybuilt, aseuminggeneration of a list of 16 topics that might be ctudiedthe6e seminars.A, A. Browman on what sort of bon factory could beLAMPF as an injector. As mentioned, this and other~uch subjects will be discussed in detail by Darragh Nagle. Also,E. W. Hoffman reviewed what is presently achieved in kaon and antiprotonsecondary beams. The fluxes obtained depend upon prtiary beam energy,but there are “knees” in the production cruos sections for low-energyii’s around 10 GeV and for ~’s around 25 GeV. It was emphasized thatpre~ent-day kaon beams are strongly contaminated by other particles,mostlv pions, even after one etage of mas6 separation. TIiisproblemof beam purity is very Important and must be faced if the full use ofIncreaoed primary beam intensity is to be realized. In the courseof the seminar we returned to this subject a number of times, as youwill see, and we now feel this is a soluble problem.January 29D. D. Strottman reviewed K% and K+-nucleus physics. The situationwith respect.to “exotic” K% resonances is experimentallymurky, butthere are theoretical groundf3for believing such resonances exist, inbag models or otherwise. FG. d-nucleus scattering, the weak Ainteraction suggests multiple scattering approaches are better Ioundedthan for r-nucleus scattering. Glauter model predictions of elasticand inelastic scattering cross sections were presented.” The subjectof I&-nucleus ac~ttering will be discussed by E5senstein and Tabakin,the next two speakers, so I will not say more about this.February 5B. F. Gibson reviewed the status of hypemuclei, a form of nuclearmatter in which one nucleon is replaced by a A (or Z) hyperon. Severalpossible reactions for producing hypemuclei were discussed; the (K-,m-)reaction is currently of most interest. Physics to be learned fromhypernuclei includes hypernuclear matter Itself, aspects of the hyperon-nucleon interaction, and perhaps properties of ordinary nuclear matterfrom use of the A as a “test probe” unaffected by the Pauli principle.The reac.ion mechanism of recoilless A production, in (K-,lT-),is some-what controversial, but good experiments at the “magic” beam momentumof 500 MeV/c are yet to bz done. There are some very recent Indicationsof the extstence of Z-bypernuclear states. The corresponding “magic”momentum for Z-states is 300 MeV/c; presently no channel can providesuch low-energy kaons. Hypernuclear physics has been reviewed at theICOHEPANS session this rnr,rningby Povh, and will also be discussed byDover on Friday afternoon.February 12C. =Hoffman reviewed the BNL Workshop on the AGS Fixed-TargetResearch Program, held last November.5 We have just heard of Brook-haven’s plans in this regard from May. We also discussed at this timethe CERN program on antiprottm physics, which will be described in somedetail tomorrow by Gastaldi.February 26R. L. Burman discussed the neutrino facility that will be proposedto take advantage of the proton shortage ring (PSR) at the LAMPF WNRfacility. Such a short duty factor use of the PSR is very compatiblewith the neutron the-of--flight prcgram of sclid state investigations.March 19, March 26, and April 2Discussions by R. J. Macek, H. A. Thiessen, and E. Colton (ArgonneNational Laboratory), respectively, on the design of low-energy separatedkaon beams. Based on experie~ce, it is necessary to collimate at asecondary focus to bprove the quality of such beams.April 6P. Herczeg reviewed the status of the CP-violation parameters inkaon decays. There is renewed Interest in this subject because ofgauge theories which have natural CP-violation built in. Of the“classical” suggestioi~sfor the origin of CP-violation, the KL + 211parameters, together with the limit on the neutron dipole moment, tendt~ rule out all but the “superweak”model. The differences between theKobayashi-Maskawa gauge model and the superweak theory are small, butmight be measurable in the future. As mentioned, Herczeg wiJ.1expandon thi~ subject in his talk tomorrow.April 16H.‘A. Thiessen xeported on a meeting held at BNL to discuss animproved kaon beam and spectrometer there. (See talks by May andHungerford at this Workshop.) A. A. Browman then made a number of com-ments on a kaon facility at L&fPF and gave some rough cost estimates.May 14M. M. Sternhe3m (Universityof ;tissachusetts,Amherst) reviewedthe physics of kaon”.cand exotic atcms. This subject will be discugsedin the ICOHEPANS program on Friday afternoon by Dover.May :7B. Povh (Max Planck Institute, Heidelberg) spoke informally ona number of subjects of interest to him, mostly in response to questionsfrom the floor. His recent experience in ~ experiments was emphas:Lzed.!?3!uAn informal discussion of where we are znd what we should do. R. L.Burman discussed other propos~ls from other laboratories that are likelyto be coming soon before NUSAC for consideration. G. H. Sanderspresented, at some length, reasons why we at LAMPF should not build akaon factory. Arguin~ from the physics program outlined i~he Bowman-Gugelot-Nagle report, he pointed out that other, present-day facilitiescan satisfy many of the stazed needs, at least for the nuclear physicsproblems posed. He then asked if there is an alternative future projectfor LAMYF that might be more interesting. One possibility might be asecond proton storage ring, possibly with variable energy, for reinfec-tion into Area A. H. A. Thiessen also mentioned some possible smallerprojects, such as additional experimental areas for LAMPF.Wrap-up sesston for Spring, 1979. R. R. Silbar discussed mat:erialhe sent to P. D. Barnes for the prepaxaticn of the NUSAC FacilitiesSubcommittee report on kaons and antiprotons. This was a somewhatpersonal distillation of the work of this seminar, particularly as itrelates to the fomnulation of aor elsewhere) in this subfield.recommendations given below.SUBJECTScore program for future work (at lASL,This material forms the basis of theNOT YET DISCUSSEDIn the coming year, after the KFWS resumes, a number of otherphysics topics will be dealt with more fully. These include:1.) What can be learned in gen~ral from rare decays of kaon~~?(An extensive program investigating rare plan and muon decays hasbeen underway at LAMPF for some time.)2.) What neutrino experiments can only be done with kaon factorybeam Intensitiett?What are the requirements hposed on a neutrinoexperimental facility?3.) How big are the advantages of studying pion-uucleus -tatteringat energies well abcve the (3,3) resonance?4.) Are there novel nuclear chemistry experiments to be done ata kaon factory? For kaon-induced reactions, a severe problem could bethe pion contamination in the beam.PROPOSED CORE PROGRAM FOR IASLPARTICIPATION IN KAON AND ANTIPROTON PHYSICSThe following is a suggested program, developed together withJ. D. Bowman and D. E. Nagle, for building up some LASL momentum inthe direction of eventually building a bon factory extension to WF.The program is not yet official nolicy of the Los Alamos ScientificLaboratory management, nor is it even universally accepted by all theKFWS participants.Near Term ProlectsThis means activities that would be undertaken in the next fiveyctirs.1.) It is quite likely that a new low-energy kaon beam will becommissioned and built relativ,zly600n at the Brookhaven AGS. Thiswould presumably optimize flux and purity to the extent possible atgiven present AGS intensity. It would be reasonable for LASL to par-ticipate in the design, but not the construction, of this new beam,This would naturally fall under activity of group MP-10; in fact,H. A. Thiessen has already been involved in preliminary discussionsof this beam (see seminar precis for April 16). Perhaps as much as0.5 SMY (Staff Member Year) could be invested by LASL in such advisorywork.2.) In the next two years it would be useful for LASL to becomeinvolved in user-group experiments with kacinsand antiprotons at otherfacilities, such as BNL. Two experiments come to mind in conjunctionwith further exploratory work on a boil factory.(a.) The LAMPF no spectrometer could be easily transportedto BNL and applied to study the interesting strangeness-changing, charge-exchange reaction (K-,ITo)on nuclei.(b.) Production cross sections of @, ~ (and also ~) as afunction of beam erergy, laboratory production angle,und a~on!icnumber (target) are only roughly known atpresent. Our present knowledge corresponds to thatat LAMPF energies before we carried out the (much-clted) LASL experiment in 1969 to measure @ productionin detail at 730 MeV at the Berkeley 184’ Cyclotron.It would be useful for future beam design studies todo the same for K’s and ~’s.An est~ted level of effort for the two experiments would be about5 SMY*S each. Perhaps some of the work can be shared with one or moreuniversity user groups.3.) The “reproposal study” of kaon factory physics, as representedby this Seminar, should be continued. The basic question to be ansm.wredIs whether the higher intensity of a kaon factory is ~eally needed to dof,nterestingnuclear and particle physics with K’s and p’s. It will soonbe necessary, however, for some members of the Seminar, to participateusing more than bootlegged time. To this end proposals for LASLInstitutional Supporting Research funds have been submitted by bcthMP and T divisions, each asking for 1 SMY of support in PY 80. Physicstopics to be studied next year should include more detailed investi-gations of some of the subjects already discussed this last spring,as well as the subjects mentioned above as not yet having been touched.We also plan to look into a number of facilities-related questions.4.) It is desirable to increase the participation of other LASLDivisions and the medium energy physics community in these discussions.One way of achiering the latter is to encourage long-term visits byuniversity peopls on sabbatical leave. The visitor would devote moreor less full time to consideration of one of the above-mentioned topics.5.) If the suggested activity in Items 1.) - 4.) generatessufficient enthusiasm and momentum, we would begin to prepare a kaonfactory proposal, presumably not unlike the “Blue Book” proposal forLAMPF in 1965. This might already begin three years from now and couldinvolve perhaps 10 SMY of effort and extensive collaboration with thenuclear and high-energy physics communities.Long-Term ProjectsThis refers to activities five to ten years hence and assumes wewill have decided that a lcaonfactory is worth proposing (Item 5. above).The design and proposal would be completed, and enlisting communitysupport would begin. A political question to be answered is whetherthe expense of such a large project could be shared with some otherccuntry, such as Canada. If the project is authorized, many peoplewill be involved in the construction of the ring and experimentalfacilities for many years. During this time, however, it would be usefulfor LJ4SLto continue doing kaon and antiproton experiments in the user-group mode at other facilities. One experiment every two years mightbe a reasonable level of effort. l!hiswould be valuable experiencethat would ease the transition to doing physics at the kaon factory.CONCLUSIONSTo summarize our first semester of study in the KFWS at Los Alamos:1.) A k..aonfactory at TAMPF is technically feasible, but expensive.2.) There appear to be many interesting physics questions thatcan be addressed with such a machjne.3.) Tileimportant task before us is to decide if the physics tobe learned warrants the expense and effort needed to build a kaon factory.As a result of a rather encouraging five months, we at Los Alamoswill continue to pursue this line of development. The RYWS will bemeeting again in the fall.REFERENCES1. J. D. Bowman, P. C. Gugelot, and D. E. Nagle, Report to the LAMN?User’s Group Long-Range Planning Committee, Sept. 1978.2. J. R. Richardson, pl~sentation to the 8th Inte~mational Conferenceon Cyclotrons and their Applications, Bloomington, Indiana,Sept.1978; M. K. Craddock, C. J. Kost and J. R. Richardson, ibid.3. Yu. G. Basargin, et al., Sov. Phys. Dokl. ~, 229 (1973).4. D. J).Strottman, LASL Report LA-UR-79-398 (to be published).5. L. Ahrens, et al., cd., Workshop on the AGS Fixed-Target ResearchProgram, Nov. 1978, Brookhaven Report BNL-50947, UC-34d.

Report on the Los Alamos Kaon Factory seminar: physics

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Report on the Los Alamos Kaon Factory seminar: physics

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